The whole argument about providing winter heat bears consideration on both sides of the fence. Chickens do well in cool temps, even in cold temps. And it's my opinion that more chickens die from issues related to excess heat than do from excess cold. That being said, there are extremes of cold that do need to be looked at. Many BYC flocks are in small coops that do not allow enough head room for good ventilation. The chickens are roosting on a narrow perch that does not allow them to be flat footed so they can cover their toes with their belly feathers. Their heads and combs are very close to the wall or ceiling where the moisture from their breath condenses and freezes on every near by surface, including their combs and wattles. The common argument goes that chickens have been surviving very well for hundreds of years without extra heat. So, why should they need it now? Hundreds of years ago, most flocks were kept in a barn with the rest of the livestock. Perhaps cows,a few horses, sheep or goats. And there was a hay mow full of hay. A hay mow produces lots of heat all by it self. Not to mention those large 4 footed beasts. There was plenty of opportunity for the chickens to bed down in a deep layer of hay, and soak up some heat from the larger animals.
Disclaimer: LG, I'm not trying to start and argument with you here - just sharing my experiences with some of the things you've pointed out. We all have different setups and circumstances. I am sharing mine because the OP is from the same state as I am so our weather is similar, and it's possible that what I share could be helpful to him. We all just want to do what we feel is best for our chickens.
IMO, the decision to provide heat needs to be based on common sense. When the temp goes below 0* F for days on end. Personally, I would not call this a consideration for supplemental heat. If they're inside and it's dry (not too much extra humidity) and it's draft-free, 0* F is tolerable. At least my chickens seem to be able to adapt. They continue to scratch around in the bedding, eat, lay eggs, do their chicken thing. It can be around 10* warmer inside a snug, draft-free building than outside. I do notice a difference when I go into the coop from outside. I should note that my coops are shed type buildings. They're both about 8' wide, one is 12' long with an 8x4' storage area, leaving an 8x8' living space for the chickens, the other is about 16x8', all living space, built so I can divide it if I need to. They're both about 7' high at the peak of the roof, maybe 7.5'. When the water won't stay thawed for more than a couple of hours at a time. I use a heated dog dish to keep my water thawed. It works great. When the bedding freezes into a solid block, when poopsicles pile up on the bedding in frozen stalagmites and those poop bedding piles get to be almost 2' deep. We've had the poopsicle issue. I clean them out when we get a warm enough day to soften them up so they're removable. I don't let their bedding become a solid rock. I keep plenty of good, fresh bedding (I use straw) in the coop, so they can snuggle down into it. I just pile it on top of the old stuff and clean it out in the spring or summer. When the perch is covered with a solid chunk of frozen poop. They choose to roost in the rafters (2x4"s with the skinny side up - they have roosts with the wide side up that they ignore) and the poop falls to the floor - creating stalagmites and poopsicles. When the eggs freeze and crack, even if you go out to gather them every 2 hours. That does get annoying. I don't like to use them when they have cracked in the nest because of the bacteria, dust from nesting material and what have you that may end up in them, but that's my personal opinion. Others who have the same issue have no problem using them. Personal choice. When the chickens become lethargic, their combs and wattles are bloody from frequent freeze/thaw issues, and most importantly, when they are eating less feed instead of more feed. Have you personally seen their combs and wattles become bloody from frequent freeze/thaw issues? This is not a challenge, it's an honest to goodness question. To me that's an indicator of a bigger problem somewhere. In my 30-some years of chicken keeping in MN winters, I have never seen such a thing, so I am wondering how that happens. Even when I was using heatlamps and keeping my coop shut tight and the coop was full of moisture I have not seen that. My chickens do slow down a bit when it gets into the -20's and -30's but their feed and water consumption does not decrease. That's an indication that they are NOT doing JUST FINE without extra heat. Common sense needs to be the rule when deciding when or how much heat to provide. I completely agree. IMO, I will provide a bit of heat when the chickens become lethargic and their appetite becomes depressed. I would consider it in those situations. I just haven't seen that yet. It doesn't take much. Last winter, they had some supplemental heat in the form of a heat lamp for several weeks. The previous winter, when they were in a much smaller coop, I gave them a flower pot heater. Common sense must rule here as well. In both instances, the extra heat took off a bit of chill. Perhaps bringing the day time temp up to 10*, 20* if it was sunny. Besides supplemental heat, what can we do to make the coop more comfortable when the mercury drops below 0*F for days on end? Extra hay/straw. Yes - it's nice for them to have that to snuggle into for extra warmth when it's super cold out . And most importantly: plenty of natural light. I have all south facing windows in my coops. The one I have set up for winter use (outlet for the heated water dish) is also painted white inside. The days are coldest when they are dry and sunny. Good solar gain will help immensely. I also like to keep my green house available for the chickens during the winter. I fill it full of leaves, and they make daily pilgrimages to the green house for dust bathing and scratching through the leaves. That's a great idea. I'll bet they just love that! There are lots of heat options. Heat plus flying, jumping animals, plus lots of dry dust/dander/feathers/ chaff floating through the air is a recipe for disaster. Take a moment to dust off your heat lamp or other heating element every day. Check the electrical connection. And secure it in place, in a way that it can't be bumped out of position to contact a flammable surface with 3 different methods.
Finally, know your climate and breed options. Exactly! That leads back to the common sense thing. Birds with small combs and wattles do better in cold climates. Birds with pendulous combs and wattles (Think leghorn!!!) are designed for warmer climates. And, IMO, feather footed birds don't belong in our cold climates where their foot feathers can get caked with frozen mud and ice balls. Of course, YMMV, and I'm sure I'll hear from lots of folks who say their feather footed friends do just great in the frozen tundra.
