Distilled Spirit

You do not get hit by any boulders if you stand under the pipe (or was it a lantern?) next to the door to the library, which will open after you defeat the boss. You can one shot bronze locust with a stone spear (at least, as a hunter). You can spam flint spears at the boss untill it dies - only took ~20 for the whole dungeon. Armor may be needed for your first completion. But you get some heavily damaged bronze armor from the guard room - more than enough to carry you all the way to the boss. Just set your spawn next to the library and spam, spam, spam!

Stilt/Bellhead shivers are. At least considering the amount of loot they drop. Building a mob farm in the caves, near the mantle, is the best way to go. Just collect all you can find in a pit/pits, separate abovementioned shivers, kill them and seal the pit. New ones will spawn. Rinse and repeat. 4 gears on average per shiver and tons of Jonas parts will earn you a ton of gears, both ordinary and temporal, in no time. And you'll get closer to that sweet terminus teleporter. Temporal storms are surprisingly bad as a source of any resources. As for the pit design, it's best to hit enemies from below. Turn the bottom into a fishnet with a chisel, but be wary - mobs do walk through chiseled blocks at times. They can push each other through 2+ block wide solid walls of chiseled blocks. Most noticeable in shivers, so make a pit at least 3x3. I have made a main pit (5x5) and connected it to 4 smaller pits (3x3). You can use fences and gates to lure enemies inside. Just make sure that the cave is no wider that pit width + 1-3 blocks on each side. Helps funnel the shivers inside. Some distant extra pits can be useful to trap bowtorns, if unable to lower the ceiling.