Quail will fly straight up if startled thus making it well nigh impossible to keep free range, for their own saftey. They like to scratch around the floor and don't need flying space.
They lay throughtout the Spring and summer, usually one egg a day each, sometimes two. I'm told that one can tell which quail layed which egg by the markings on the egg as they are always the same. They don't go broody and they won't sit on their eggs so if you want to hatch them you'll have to use an incubator or a bantam.
We sell our surplus eggs at the farm gate for £2.00 a dozen. We don't have that many so we'll never make a fortune but I guess they pay for themselves. We find that lots of people want the eggs for hatching, ours aren't fertile as we don't have a cock bird. It would appear that they are primarily hatched as food for raptors, in fact our birds were destined for owl food when we bought them. I understand that they are culled at six weeks.
They are endearing little characters and their call is quite charming however they really, really don't cope well with stress of any kind.
Stressful situations like overcrowding can lead to agression which if blood is drawn can end in canabalism. If you have a sick bird I'd always recommend seperating it before the others literally peck it to death.
We have a "sick bay" where three hens now live peacefully together, each one of them had to be removed from the main hutch for a variety of reasons and it seemed safer not to try and re-introduce them when they were fully recovered.
They are fed on chick crumb, layers pellets, seed, corn, scraps etc. They love a bit of greenery and I actually grow chard and spinach near their hutch just for them.
The hutch has flower pots turned on there sides for little resting places, leylandii branches for shelter and some old CDs/DVDs hung from the caging to give the quail something to peck at rather than each other.
They do need constant access to water which can lead to a bit of a problem as they will walk in the water.
The wet feet then pick up bits and before you know it you can end up with a quail with a ball of "soil" set like concrete on it's toe. This has to be carefully soaked and removed or the bird will end up losing a toe.
That's all I can think of for now, hope it helps.