Chickens are way tougher than us. They have thick leathery hobbit feet and snow doesn’t hurt them. If it did, they wouldn’t walk on it. Once the flock gets used to the snow, they willingly walk on it. If it melts and then snows again several weeks later, they’ll usually be afraid of it all over...
Stepping on the snow won’t make their feet cold (not enough to bother them). It’s just that many chickens are afraid of the snow... because they’re chickens. :p Some of mine go out, others don’t, but if the others can see the some, they eventually come out too.
Some people don’t like straw (not clear as to why). Some people don’t like hay because it can get moldy. I use both and pine shavings, pine needles—whatever dry carbonaceous stuff I can get. If you pile it deep (inside or out) it’s a good idea to mix it up with a pitchfork or similar. Just toss...