Thanks guys - yeah, I think part of the problem may be a lack of containers - I'm going to look at getting a second craftsdwarf's workshop created solely to create rock pots. I'm also going to look to get my egg industry running properly so I can eliminate the possibility of the food shortage causing this.
You'll want to go into the stock(p)iles menu and set your reserved barrels to 10+. That will mean that if you have less than 10 barrels empty, currently empty barrels can only be used for tasks requiring barrels (brewing, building workshops, maybe also milking). Reserving 10 barrels will usually mean you'll have at least 100 booze after you set your brewery on repeat.
Don't forget that dwarves need variety when it comes to booze as well. If they get tired of plump helmet booze, they'll refuse to drink it and drink water instead. They'll probably drink it if there's no water once they get dehydrated, but preferring water will lead to your supply of fresh water running out faster.
If I construct a pit 2 z-levels below ground and channel a water source into that, then use a screw pump to pump that salty water up into a constructed reservoir (ie, walls and floors, not just hewn rock or clay), it should be usable as a water source without my having to tunnel all the way down to the caverns and make a well within the first year of embark?
No experience with salt water myself (I've never done an ocean embark), but what I get from the wiki aritcle on
salt water is that if you build a constructed underground cistern in a salt water biome, the ground has already been marked as salty, and you'll end up with salt water. If you've got a pond that isn't salt water, though, that is in a fresh-water biome, and you can build a constructed cistern underground entirely in that biome, fill it with a screw-pump, and get fresh water, regardless of what kind of water was pumped in.