I agree with everything except the roosts. If it's reasonable to expect that chickens are much like wild birds in the fact they can fluff up their down and keep themselves warm, then, much like wild birds they can roost on a round roost and still keep their feet warm.
Been using round roosts for many years without cold feet being an issue. My birds prefer round roosts as this is more comfortable for their feet. If you will notice the natural action of a bird's feet when you bend their legs is for the toes to bend also. This is a built in feature in birds to help them sleep as they roost without falling off a limb. Their feet sort of lock into place when they are in this position so they won't have to keep gripping that limb all night. It's comfortable for them.
Bending the knees and keeping the toes splayed is not necessarily an easy stance and they cannot grip the roost, meaning they must balance on a 4 in. wide beam all night. If it is a bantam breed, this presents no problem. If a standard breed, this means they have to balance their bulk/length of approx. 12-14 in. on a space that is 1/3 that big. This is not conducive to relaxing enough to actually get good rest, IMO.
All my roosts are designed to follow the natural curve of my chicken's talons...not broomstick width, but tree limb width.