Welcome to BYC. I live in Lucerne Valley, Ca. That is the high desert area. Our winters can be cold...30's. I do not have a barn. My birds are in coupes outside. I put OSB boards around the coupes at this time, the coupes are wooden frame and wire. They have a roof of OSB. They are protected from the rain, for the most part, but when it is cold, it is cold. Yes, I loose a couple of birds in winter. Most of them do quite well.
You see, they also have extreme heat in the summer as it can get to 115 here, but it is not a humid heat so the shade takes care of the problems.
My coupes are pictured on my member page, which is found under my screen name.
I do move my birds around. They adapt. I have noticed however, sometimes a bird will be raised with another bird and choose it as its buddy. They do better staying together. When one dies, the other bird will miss its buddy. Yes, they have personalities and you will learn that soon.
Best of luck to you, it is a big chicken world and it is hard to limit yourself...you will see.