Depends on the breed. You want ventilation up higher than the chickens. You do not want drafts in the winter. So i feel a closed door at night is a must
You should consider adding Wellsummers. They are friendly talkitive birds that lay well and have the most stunning Roosters. Very friendly birds and nice dark brown eggs. Not as dark as a copper maran but many lay speckled eggs that are very cool
Often hatcharies have poor breeding practices which is fine for normal pet quality and egg producers. But bantams are also more susceptible to birth defects when not bred properly. Before i started my line of D Uccles I had gotten one from a hatchery with club feet and some with cross beak...
If you hold a bird under your arm the etxtend extend its neck as far as it goes forward comfortably. Then with a quick pop forcw the head upward. It seperates cervical spine from the brain stem causing instant death very humane
You need to make sure whomever you purchase chicks from is npip certified. Hatcharies are fine for production chickens but if you want to show or breed. Buying from an NPIP certified breeder is the way to go. I would never buy Bantams from a hatchery EVER