Some beginner questions!

I'll answer the ones I know

1. Quails require less space than chickens. I'd say one square foot per quail would be fine.
2. Quail do need a totally enclosed coop because they can fly to some extent. Also, they are fairly clueless as far as escaping/evading predators.
3. My quail would sometimes lay once per day. Other times nothing (probably because I didn't provide heat/light during winter). If you are raising them for the eggs, I've heard that Coturnix are by far the best.
4. I never sold my eggs, but I've heard they sell for more than chicken eggs to the right buyer.
5. Depends on how big it is. I had four quail in an old rabbit house that was about 4'/1'6"
6. I fed my quail regular chicken feed, but you can get better laying performance with higher protein food.

Hope that helps a little!