Ceiling height depends on whether you are going with a pen or aviary style. 12 -14 inches minimum is good for a pen. Aviaries can go as high as you like. My aviaries are 6 foot in height.
My winter aviary is backed up against a greenhouse where I have the quail coop. That way they can get out of the weather. I found that quail don't use ramps like chickens and this ramp is only going to take up space. So I set up concrete blocks and bricks to make some "hop up steps" if you will. They seem to prefer to hop or flap a few times to get up. This is the only pic I have that semi describes what I am talking about. LOL
They do not use this coop unless the weather is bad and even then, they prefer to sleep in the aviary until temps get down in to the single digits. But it is a place to hide and hunker down in winter.
Quail don't use nest boxes either and prefer to make nests out of hay on the ground. I use over turned buckets for the breeding caged quail. The lose quail get to make nests all over and where ever they like...