Thanks very much to both JackE and WthrLady; your explanations help a lot.
I hadn't made it very far into that thread you linked to, JackE. 43 pages! But I did go look at your page 4 photos, which are just what I needed, and I'm going to recommit myself to reading that thread.
I've got someone at my library trying to find an interlibrary loan copy of Woods' 1924 book (they have to go out of state); Amazon's used prices are as high as new prices, and I didn't want to invest in that if it wasn't going to offer more of this sort of information than the first book did. But, based on your review, I think I need to go ahead and buy it. Thanks!
WthrLady, apparently what's super-easy for lots of people just isn't easy for me. I gave up on building without help when I tried making just a basic 4x4 box coop, of which the preliminary pieces were out-of-square in every dimension, and somehow mismatched in size, despite what I thought was pretty good effort. (Granted, I was working with scraps, rather than buying large pieces and just following a recipe.) I expect that building is a skill that improves with practice, but I just don't have that much energy to work with.
I've been to Habitat Restore many, many times, and have pretty much decided it's not worth the gas and time. Quality materials of the sort I need just aren't available. Employees say that when good lumber, good flooring, and the like do come in, they get snatched up instantly. Maybe, like with garage sales, good quality stuff is more common in wealthier locales.
I hate to keep harping on limitations of money, energy, and ability; I hope I don't drive you all away. Poverty plus disability is a nasty and discomfiting combination. I expect that once I'm fitted out and actually raising chickens, I'll be fine.