No heat! How much would you be willing to spend for a down and feather jacket as well constructed as a chicken's? Then how long would you be willing to stand in a warm (not necessarily heated, but warm) building with it on, zipped up tight and buttoned? Yeah, same here! Good ventilation seems contrary to battening down all hatches and sealing up the coop too, but they put out so much humidity with their respirations and droppings! If that can't get out along with all the ammonia build up from chicken poop, that dampness settles around them and it's the perfect recipe for frostbite. Now, if their feathers are ruffling, that's too much draft. Go back to that coat - keeps you toasty warm no matter how cold it gets until the zipper breaks and all that trapped warm air escapes. The goal is to keep warm air trapped in their feathers and down and keep moisture off them. That equals chickens superbly suited to handle the cold.
I detest heat lamps so much I won't even use them for newly hatched chicks! Excessive heat, fire risk, inability to maintain steady temperatures, no cool spots, heats everything around them, and light 24/7. <shudder> Every year right here on BYC we read about someone who lost or almost lost their coop and chickens to a heat-lamp caused fire. So my chicks don't get a heat lamp - even when I brood them in temps in the teens and twenties with snow flying. And I live in Northern Wyoming not too far from Yellowstone Park!
As for warm water, as much as I respect @oldhenlikesdogs and her knowledge, I won't give warmed water, either. Some folks bring out warm oatmeal to them on cold mornings. I can't make myself do either - when that warmth hits the cold it puts out vapor, and that vapor settles as condensation on the closest thing to it - the chickens' faces. So their combs and wattles are damp, then the cold air hits them.
Just use your good common sense and you'll be fine. You want to keep them dry, out of direct drafts, in a clean well ventilated environment. They'll do the rest. They'll sit on their feet to keep them warm if they have flat sided roosts. If they have a hay or straw bale to stand on, even better. If it's windy they'll move out of the wind. They want to survive as much as we want them to survive! You can block the winds with a windbreak on the side you get the coldest wind from, and keep out blowing snow. Your biggest issue will be gathering eggs before they freeze, but that also ensures that you'll be out there a few times a day and can see how they're doing! You've got this!