I wanted to wait until after the craziness of the holiday to chime in on wintering.
I do not have heat to the coop, we have our power go out occasionally and I don't want them to rely on heat. Instead, I use the deep litter method for their bedding inside the coop. Deep litter will actually warm the coop a little bit in the winter. I start building my "winter bedding" around August. I clean it all out in the spring and put it in my compost pile to add to my garden in the fall as well. I use pine shavings for litter and add a few handfuls of Coop Refresh every time I add litter. I add litter when it starts to smell like ammonia at the litter level.
I have a large window on the south side of my coop and I cover most of that with plastic when it starts dipping into the 30s. I have ventilation on the north side of my coop and I'm looking at getting a small solar exhaust fan for the top north wall of the coop, as well (to aid ventilation).
I don't keep food or water in my coop, especially in winter. I learned the hard way that if my larger waddled girls dip their faces in a cup of water in the winter, they'll get frostbite, so I put a bowl of snow in, instead.
I switch my waterer in the winter, but I haven't been thrilled with what I've found, so I'm going to switch to a nipple waterer in the winter with a heating base underneath. I run a heavy duty extension cord out to the run and keep it plugged in. The ones I have found will only turn on at certain temps. I have the waterer sitting up on top of a plant stand (in the summer, it hangs).
I purchased a heavy duty plastic tarp for more permanent wraps for the run last fall. Loved them! They were easy to clean and have grommets along them for easy put up. I wrap nearly my whole run. I also purchased straw bales to block the wind at the end of my run.
Feel free to ask any questions! Chickens are really hardy in the winter! I worry more about heat in the summer, but I was also worried about winter my first year.
Links below:
How to Deep Litter (don't use coop recooperate, tho, it has essential oils which are typically not recommended for chickens, but the other info is good):
https://www.google.com/amp/s/www.getstronganimals.com/amp/deep-litter-method-for-chicken-coops
Example of a chicken water heater (I don't like mine because it has a soft base that has caved in, so I need a new one):
https://a.co/d/0fJdrdUR
These are my tarps to block wind:
https://a.co/d/02CrO75e
Coop refresh (I add a couple handfuls when I add bedding):
https://a.co/d/04yvAZ8Y
These are the nipples I'm looking at for the waterer:
https://a.co/d/0eDpnfSy
Here are the stands I use for my waterer:
https://a.co/d/0brrIepG