williams_482

I realized I only answered part of your question.
Farmland needs to be within three blocks of some sort of fresh water (source or flow) to get any moisture from it, but as you saw it declines by 25% for each block of additional distance. 
Farmland with 75% hydration because it's next to water is usually fine. You can water it, it will grow faster, but it's usually not worth the effort.
If you are planning to rely on a watering can for irrigation, it's still best to make sure there's water within three blocks when you first plant the seeds. There's a bug where seeds planted in completely dry soil will grow half as fast over the life of the plant even if they are subsequently watered. In my first world I (unaware that better soils existed) planted my summer crops in dry, low fert soil and watered them regularly, but only about half of them reached maturity before freezing to death. I did have the fun experience of seeing my rye plants be stunted by both heat and cold though, so that was interesting. 

You have two basic options for using those tools:
1. Continue your material progression. Go looking for tin or bismuth and zinc to create bronze, and then use that bronze to get some iron.
2. Use the nifty new tools you've unlocked for other activities. Your saw unlocks boards, which unlock new building materials as well as a number of agriculturally useful items like buckets and troughs. The chisel and hammer unlock the quern for grinding flour (for bread and pies) and limestone (for processing hides into leather), as well as chiseling blocks directly to add detail to your builds. 
Whichever of those sounds most interesting would be a perfectly good direction to go. 

Both anvil parts do require five ingots, but it's quite easy to waste voxels by stacking new ingots beyond the maximum height of the work piece. Add one ingot at a time only after the previous ingot is spent, completely filling out each layer from the bottom up. And definitely don't destroy any voxels until everything else is done. 
The anvil bottom requires slightly less than five ingots worth of voxels, and is relatively easy to complete with just the five. The anvil top, meanwhile, requires exactly as many voxels as five ingots will give you, so you have zero room for error. I often get this slightly wrong and have to use six ingots. 
There's a detailed set of instructions in the wiki which I found to be quite helpful.