Also a fan of coop first, then brooder, then chickens. and if doing an integrated covered run, placing the brooder/quarantine at the opposite end from the coop has some advantages for everything but biosecurity. Sick birds really should be as far away as can be safely arranged.
Yes, the birds in the "grow out" tractor spend the night there. Its part of my "see & be seen" process before they are integrated into the main flock.
As for predator protection, I COULD have done the whole thing in cattle panel and hardware cloth, but instead used chicken wire in places...
Apologies - I assumed otherwise. Yes, that is PLENTY of space for your bird count.
Greetings, fellow free ranger! Your birds will be glad of the space.
End result of said coop is not particularly attractive, so if you have an HOA this is likely a "no go", but it was fast and relatively inexpensive which is what I needed at the time.
I have a raised chicken coop / duck house (about 100' sq f, ea of two floors) and a goat shed (almost 160 sq ft)...
Zero F isn't particularly cold (as chickens account such things, anyways). 64 sq ft is tight but potentially doable. More so if its an 8x8 square which will help keep one dominant bird from controlling the whole space.
8x12 or 10x10 would be much better.
The "thumb rules" as a starting place...