For babies I use plastic totes that are tall enough to have perches/branches. They like having hides that are up off the ground but will use any hide. They especially like to stuff themselves into small spaces. Adults do fine in 2x2s or whatever you give them really. Cohabitation is fine, but they aren’t very smart so separate for feeding or you’ll turn around and one will have the other one’s head in it’s mouth 
Humidity is a huge factor in caging, you don’t want them having bad sheds or you’re going to bleed trying to help them shed. Their skin isn’t like most snakes, it’s thick, it sticks hard, and it’s difficult to soak them enough to get it come off super easy like a ball python will.
For meal sizing, throw all the common guidelines out the window. Bigger goes over better with them. A shoe lace size tree boa will eat mouse hoppers that you’d never guess they could actually swallow let alone digest. Don’t go nuts but there’s nothing wrong with a meal twice the girth of the snake. They do eat a lot. Adults will eat a medium rat every week. They aren’t inclined to obesity like most boids, they have a pretty fast metabolism.
I keep mine ambient at 82* and they do great. As long as they aren’t too hot or too cold, they’re not super thermally sensitive.
This is animal specific. CBB or Imports. Some of mine are no problem at all. Others will die for the cause before they stop taking swings at you.
They’re designed to snatch fast moving avians, you give them a target, they’re going to try and hit it. They don’t have a lot of room for computing in their tiny heads so essentially you have to be on guard for a bite at all times when working with them. If you get lax with them, they’re going to tag up.
They’re super rewarding, and I recommend them to any intermediate keeper, but they bite. It’s not all that uncommon to find tree boas that aren’t very bitey, there is just no way you can guarantee getting one of those. Essentially, just assume they bite, and treat them like it and you’ll be fine.