You might already know about flat board roosts to prevent frozen toes.
I'm new to PA so winterizing the coop will be a new thing to me also, but in general, Chickens are cold hardy birds. I think there are a lot of cold hardy breeds out there.
They say that moisture is the coop's worst enemy in the winter. Imagine yourself being wet in the cold vs dry in the cold. So the chickens will want fresh air moving through the coop without it being a wet draft.
Here in PA, all of the dairy barns are built with the open side facing one direction and the closed side facing the opposite so that rain never blows in. However that works in Colorado will be beneficial to you as well-- on which sides of the coop you place a vent or window.
As far as water heaters- if you have electricity in the coop, you may be able to use an aquarium heater to keep your water 5-10 degrees above the inside of coop temp. Or if you are having a lot of birds- maybe even a livestock water heater will do. This will depend on your inside of coop temp vs. the outside temp with windchill.
Somewhere online, I have even seen a cinder-block heating method that incorporated a light bulb lit inside of a cinder-block to heat the water.