LadyWYT

You can give yourself the requisite map items from the creative inventory in order to just mark the location, I think. However, you can also use /tpstoryloc with the appropriate location moniker in order to teleport right to it. The monikers are as follows, I believe:
 

Welcome to the forums! 
You will need a quern, yes, but a copper chisel can be used to craft the quern, and a copper chisel can be forged on a copper anvil with a copper hammer. The forge only requires cobblestone to craft. You don't actually need fireclay until you get to iron working, steel refining, glass smelting, and baking things other than charred bread.
Once you have a quern, you simply use it to grind calcined flint chunks into powdered calcined flint. That powder can then be mixed with red clay or blue clay to make fire clay(one unit of powder will make eight units of fire clay). To get calcined flint chunks, you will have to cook regular flint at a very high temperature in a firepit.

Welcome to the forums! Unfortunately, I'm not sure what to do here, aside from perhaps submit a bug report to the Github bug tracker. It's probably unintended behavior, as it's not exactly common to be teleporting like that.
However, before submitting a bug report on it, I would recommend disabling your mods and testing on a vanilla world, if you can. Mods are a likely suspect when it comes to strange game behavior, even if the mod appears to be unrelated to the problem at hand. Likewise, if mods were involved, the first thing you're going to get asked when submitting the bug report is whether or not the issue still occurred without the mods enabled.
As for getting your stuff back...you'll probably want to pop into creative mode briefly and spawn in the missing elk/other stuff.

Honestly, have to agree with @Professor Dragon here, in that there are just too many variables to account for. As a general rule, Vintage Story is optimized very well, and the vanilla game should run excellent on the average machine. Sometimes there's a bug or two that throws a wrench in the works, but those are usually sorted out fairly fast.
For vanilla specifically, it's going to depend on player hardware. Weaker hardware will want to turn down graphics, which usually equates to lowering render distance, lowering particle counts, lowering shadow quality, etc. It's also a good idea to keep background tasks to a minimum while playing, as they can also interfere with game performance(especially on weaker hardware).
Having lots of signs, machine parts, a ridiculous amount of entities crammed into a small location, lots of intricate chiseling, etc, can all possibly impact performance, but I would say that's really only a concern for weaker hardware, and like...a TON of that stuff packed into one's base. I would also say that's a general rule for most games, not just Minecraft or Vintage Story. The more you have going on in a single space, the more the system is going to need to work to account for it all.
It's also worth keeping in mind that for multiplayer specifically, spotty internet connection can easily cause issues while playing, although connection issues typically come with a warning box appearing in the upper right hand corner. Likewise, the bigger the server is, the beefier it will need to be in order to handle a large map with lots of players.
Honestly...it sounds like those players might just have lower-end PCs, and/or be running other programs in the background that may impact their performance specifically. Having browser tabs open, playing music, or recording game footage can all be fairly demanding on system resources. However, it's also possible that they're trying to play the game at higher settings than what their hardware can handle, and thus are encountering problems as a result. If it is a hardware problem though, I'm not sure there's much that can be done, outside of tinkering with graphics to find something more workable or upgrading hardware(if possible). While it may not be fun to do that, it's also not really fair to force other players to avoid chiseling or otherwise reasonably enjoying the game just because the hardware of other players can't handle it.
That being said...despite it being a vanilla server, it's worth checking to see if the players having problems are using client-side mods. If they are, it's entirely possible that there's a mod causing issues(especially if the mod is out of date and not otherwise known to work correctly on the latest game version), in which case they should try disabling their mods to see if performance improves.
If you've got logs available, you could also try posting them here on the forums to see if someone else can figure them out. If it's an actual crash report though, you can post that to the forums too, but that's much better submitted to the Github bug tracker for the devs to see.

If the armor durability is 0, it will no longer provide protection from incoming attacks. However, that durability is separate from the clothing durability that provides the bonus to warmth. For some reason, the clothing durability stat doesn't seem to tick down at all on bear armor, which I'm guessing is either a bug or an oversight. In any case, that's what's going on here--the armor is still keeping you protected from the elements, but not from attacks.

The first step is to disable your mods and ensure vanilla works properly. If it doesn't, you'll need to backup your saves in a separate folder and reinstall the game, then check again to make sure vanilla is working properly.
Once you've verified vanilla works as it should, then you can start adding mods back in one by one, testing as you go. Though tedious, it's the easiest way to figure out exactly which mod is causing the problem, if you've otherwise no clue to the culprit.
The only other thing I can think of to check is to make sure that installed mods are either up to date for the recent game version, or are otherwise known to be working correctly on the recent game version. Likewise, check for mods that are marked as a developer version--these mods often have issues(but not always) since they are unstable releases.

Welcome to the forums! Finding elk in the wild is possible, as I've done it a few times, but they aren't a creature I would really consider a common find. The best place to start searching is the Cool climate zone, given they prefer taiga as habitat. For a temperate start location though, you'll be wanting to search high altitude plateaus, as these are the only places that are cool enough to their liking. It's also better to stick to open grasslands, shrubland, or sparse forest, as I don't believe they will spawn in deserts or dense forests(in this case though, if they do spawn, they'll be difficult to spot).
Basically, if the climate is cool enough to qualify as a taiga, and it's a grassy area or sparse forest, it's a prime elk hunting location. However, it's easier to find a climate they could spawn in, than it is to find the actual elk themselves. Also keep in mind that you need a baby elk specifically to capture and raise in order to tame your mount, and since I don't think it's possible to breed deer like you can with livestock(I could be wrong), that means you'll be relying on a baby elk spawn specifically.
Honestly, unless you're playing Homo Sapiens or just incredibly intent on taming your own elk, it's much less hassle to just fork over some gears to your friendly local treasure hunter for a trusty mount instead. If you do try to tame your own, the best strategy once you've found them, is probably to try breeding them first(I'm pretty sure this doesn't work, but just in case!), or otherwise barbecue them and wait for them to respawn(rinse and repeat if there are no baby elk when they respawn).

I wouldn't be surprised if the feature were added someday, but I've not seen anything to suggest it's a feature that will get added anytime soon. Until then, hammer/chisel, or mods are the way to go. There seem to be a handful that exist, like this one: https://mods.vintagestory.at/show/mod/28046
I will note though, the mods that do exist are for older game versions, so they may or may not work properly. 

Should this ever happen again, it's worth noting that you can set yourself to creative mode(/gm 2) or spectator mode(/gm 3) and fly yourself out of the situation. /gm 1 will set you back to survival.
For console commands in general:
Server commands: https://wiki.vintagestory.at/List_of_server_commands
World Configuration: https://wiki.vintagestory.at/Special:MyLanguage/World_Configuration

It's definitely a mod issue. Looking at the logs might yield some useful information on which one could be the culprit, but the first step is to disable them and test on a vanilla world to see if the issue persists. Hopefully it doesn't, but I'm guessing it might, since I had similar issues once when messing with mods and had to reinstall the game entirely in order to fix it.
Once you've confirmed vanilla to be working as intended, then you can add mods back in one by one, testing as you go until you encounter the issue again. That should help you pinpoint which mod is causing the problem. The other to check when it comes to mods, is making sure they're all up-to-date for the current game version, or in the case of older mods, known to be working properly on the current game version. 
Given that it's wintertime, you might check to see if you have any mods that change the frost overlay, but that doesn't rule out a seemingly unrelated mod causing weird texture issues.

Welcome to the forums!
I'm guessing you messed with the world generation settings in order to get this. I wouldn't trash the world, but I would start over on a new save file, with something closer to standard world generation, as that will make it easier to learn gameplay basics(you'll have an easier time actually finding resources you need to progress). Once you've got more of the basics down, then then you could come back to this world for a more challenging playthrough.
That's not to say you can't play this one as your first world, but...an island that small is going to be incredibly restricting, and if the only land out there is tiny islands like this, it's going to be much more difficult to secure critical progression resources. Even more so if you don't even have cattails, as those are needed to make rope, which is used for the raft(the first water vehicle). You can use vines to make rope as well, but I'm guessing there likely aren't enough vines for that here(and vines don't regrow like cattails).

Welcome to the forums! The first thing I would check is inventory space--if you didn't have the space to hold it, it most likely got dropped to the floor. You might try clearing some inventory space and checking around his home to make sure that it didn't get dropped.
If you still can't find it, it's possible that it might be a bug, in which case you should report it over on the Github bug tracker. Do note that if you are using mods, you will want to disable them and try to replicate the bug in vanilla(you can use console commands and admin blade to speedrun chapter 2, no need to complete chapter 1 first). If the bug can't be replicated in vanilla, then it's likely an issue that's being caused by a mod.
The item itself doesn't appear to be available in creative, which is probably an oversight and worth a report. The good news is that you can spawn the rickety translocator via creative, so while you may not be able to craft it for that world, you can still access the tech itself(can also wait until you've made all the craftable parts before deleting them and spawning in the translocator).

I don't recall. It was called "Compatibility Patch" or something to that effect. I'm not even sure it's on the database anymore, to be honest. If it is, I don't recommend using it, since it doesn't actually fix the issues that Wildcraft has on the current game version. Hence why I say it makes things "work"; that is, the code might compile and it might not spit out so many errors to the server console, but you'll still encounter issues like animals not eating from troughs or getting attracted by trap bait.
I would either wait for Wildcraft to receive a proper update, or start a new world. You could also try to continue as-is, and try to find a workaround via some use of creative mode or something. 

This would be my vote, given the trader rework that is coming and whatnot. However, this also depends partly on how attached you are to the structures in your current world. I won't say it's easy to let go of a world you have so much history in, however, I would only worry about copying over structures if they are things you just can't live without. Otherwise, a new world offers a fresh slate to start anew, with plenty of space and resources to make even more memories, and screenshots can help preserve the memory of the old.

Welcome to the forums!
Smelting doesn't require a room; you just need to make sure that nothing can put out the fire under the crucible. And as @Vexxvididu already noted, the fuel you're using needs to burn hot enough, for long enough, in order to smelt the ore. It is possible to "coast" on coals, but if the temperature of the ore drops you'll lose your smelt progress and have to start over. Another thing to keep in mind that in regards to alloys, you need the proper ratio of ores in order to achieve a smeltable product; if there's no viable output the ore won't smelt. Also, the more ore you try to smelt at once, the longer it will take to smelt, so the ore can be hot enough to start smelting but you may not see any progress on the meter for several seconds, as it takes a fair amount of time to smelt large quantities of ore.
In any case, charcoal is sufficient for smelting copper and zinc, so the first things to check are ore quantity and ore ratio. Given that you said the meter still reads as "cold" despite the fire burning at maximum charcoal temperature, I would suspect that you have the wrong ratio for the alloy you're attempting to smelt(brass).

Honestly, with it being a very old world, I would submit it to the issue tracker. 
If you can manage to repair the chunks even a little at a time(it sounds like you've managed to do this?), an alternate solution is to repair only the chunks you care most about, save the builds as blueprints(or however this happens via worldedit), and then import the builds into a brand new world. For items, make a list of the important stuff on paper, and then use creative to give it all back.
Unfortunately, it's not a solution that preserves the world, but worst case scenario, it should allow you to at least preserve the builds.

Welcome to the forums! You basically have two options here, the first of which is just doing a LOT more prospecting. From the looks of the map here, you've done a lot of prospecting in a few chunks very close to home, but little more. I would suggest doing more general searches, in a 1000 block radius(more or less) from your base. Once you pick up another trace of cassiterite, then you'll want to do more localized density searches in that area to see where the best dig spot is.
The second option is to just dig at the best reading you've already found, and see if there's any ore. Poor and Very Poor readings aren't ideal for digging, but that doesn't mean that the ore in question failed to spawn, just that it's not too likely to have spawned there. Cassiterite is a common ore, so it's generally not too hard to find, even at less than ideal readings.

Welcome to the forums(and the game)!
Ultimately, the choice is up to you, but since you've not even played the game yet, I highly recommend playing just vanilla for a while and just focus on figuring out the basics first. Doing this will give you a much better grasp of the game overall, as well as allow you time to figure out which parts of the base game you'd most like to change.
Regarding vanilla options, I would recommend picking Standard or Exploration as the starting difficulty. Standard is tough, but fair, and also the intended developer experience. Exploration is less challenging, but may be the more attractive option if you find yourself struggling too much while trying to learn. Wilderness Survival and Homo Sapiens are both the hardest difficulties, and while it is possible to start learning the game on these difficulties, it's definitely not something I'd recommend for brand new players unless they really really want that kind of challenge.
One important thing to note about vanilla options, is that most of them can be changed via console commands after creating the world(though you may need to reload the world for the changes to take effect). A couple of options you might consider tweaking, are enabling the Color-Accurate World Map under the Survival Challenges tab, as well as setting a brief grace period for monster spawns under the Player Spawn/Death tab(in this case, rifts will still appear if enabled, but won't spawn monsters until the grace timer is up). You may also wish to enable the "keep inventory" option for Death Punishment, if you find yourself dying a little too often.

Welcome to the forums! Unfortunately, I'm not sure that there's currently a way to adjust the stability aside from turning off the mechanic entirely. The best fix is to just move your smithing setup to a more stable area, or else be prepared to burn a lot of temporal gears and healing items to keep your stability topped off.
If you're willing to mod, you could try one of these, though bear in mind that mods aren't guaranteed to be maintained, and may have unintended consequences. Older mods will sometimes work on a newer version, but best to make a backup of your world just in case something goes wrong.
Temporal Amulets: https://mods.vintagestory.at/temporalamulets
Temporal StabiliTea: https://mods.vintagestory.at/show/mod/27496
Chunk Stability Override: https://mods.vintagestory.at/chunkstaboverride

Yeah, if you just press and hold shift(or whichever key you have sneak/crouch bound to), your character should climb down the ladder without issue. If you're falling off the ladder while trying to do so, it's likely because you are pressing the backward movement key while descending(or perhaps pressing one of the side movement keys by accident) which will cause your character to move off the ladder and thus fall.

You'll want to be looking in taiga areas for them, as they prefer cooler climates. So searching the cool climate zones is a good place to start. They can spawn in the temperate zones as well, though on high altitude plateaus(typically grassland or sparse forest) where it's cool enough for a suitable habitat. Those would be the prime spots to look.
That being said, I wouldn't necessarily call them a common spawn, as I've only seen them in the wild a handful of times. It's probably easier to find them, than it is to find a baby one that you can actually capture and tame, since I'm not sure that deer can be bred like normal livestock species can be. Unless you're playing Homo Sapiens, or otherwise just really wanting to catch and raise your own, it's much easier to purchase a tamed adult elk from your local treasure hunter.

Okay, after taking a quick gander, you should be able to work your way out of this without using the console. First, make sure you're at full health, then go stand on the ledge outside the doorway. Facing the doorway, step backwards off the ledge and immediately press the forward movement key to hug the wall directly in front of you. It's a decent drop, but you should survive. Heal back up, then work your way down to the bottom of the structure carefully--the drops should be much less drastic from here. Once at the bottom, take a look around and be on your guard for monsters, as there's probably a few lurking around here. Somewhere at the bottom, there should be a ladder to climb, that will lead you to the path out. Once you find the ladder, simply climb it and work your way back to the upper levels.
Of course, the easier, safer option is to just switch to creative(/gm 2), fly back up to wooden platform, and then switch back to survival(/gm 1).

Yes, that is what you need to do--trap an elk calf, and then feed it enough before it grows up in order to have a partially tamed elk. From there, you can saddlebreak it to achieve full tameness.
 
You can try searching mountaintops or other high altitude places, as those may be cool enough to spawn elk that far south. Otherwise, your best bet is making a trek north...way north...and establishing a temporary base for a year or two while conducting your search. Elk are most common in cool taiga regions, typically grasslands or sparse forest(I've not seen them in dense forest--they may still spawn there but will be difficult to see). In temperate zones, this typically means poking around on high altitude plateaus.
Of course, finding the elk is probably the easiest part. It's acquiring an elk calf that's going to be difficult, since I'm not sure that you can actually breed deer to get babies.

Like @Maelstrom said, rainfall doesn't affect season length or outside temperature. What affects those is latitude and altitude.
Body temperature, however, is a different story. If it's raining and cold enough outside and you get wet, you'll get cold a lot faster than if you were otherwise dry. 

To my knowledge, bosses will ignore players who are in creative mode.
 
Try switching to survival mode; the Crow should show up, though it may take a minute or two depending on where exactly the Crow is at the time. Ordinarily, the creature patrols the waste and will circle the Tower once the player reaches that area and begins the climb. However, if you're in survival mode and it's been several minutes, it's also possible that the boss is bugged(this issue has cropped up a couple of times over the patches), in which case you should head over to the github bug tracker and report it.