Well, for both questions it will depend on how fast they grow, what kind you are getting, and how long you want to keep them in there. I find that my leghorn chicks will fly right over the edge of a plastic play pool at a week old, while my cornish x chicks are just fine and happy sitting in it for a few weeks. 1sq foot per bird should last about a month or so for the chicks.
We have used a kiddie pool and it is about a foot tall. As they get to learn to fly, we put hardware cloth over the top and eventually we make a circle of cardboard to extend to 2 feet tall, covered still with hardware cloth.