Hi Rose66,
I started keeping chickens last year and also had a "not in the house rule." The coop wasn't quite finished when they arrived so the chicks lived in a large (2x3 ft?) cardboard box in my unheated garage for about a week while I finished things. They had a brooder lamp over half the box for heat. Once the coop was finished I moved the lamp etc in and put the chicks to live in their 5.5 x 6 foot shack. That was plenty of space for them until they were well feathered and ready to go outside. My coop has "excellent ventilation" through the many cracks between the vertical 4" boards I used to make the walls and the little ones did not seem to mind at all. Those heat lamps put out a lot more BTUs than you'd imagine!
Apprapos to nothing in your question.... I would recommend using a nipple watering system as they were always getting their water muddy or into the bedding. Wet bedding = stink and disease. There are several systems... self-filling pipes, hanging jugs, 5 gallon bucket... (I use the Avian Aqua Miser jug type. You can get the same parts from FarmTek but I really like the AAM folks as people.)
Good luck and enjoy the adventure!
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Chief wrangler of 1 man, 2 dogs, 10 cats, and 19 free roaming chickens.