Actually, I read a post about a guy who made a heater for the waterer by putting a light bulb into a cinder block and laying a paving stone on top. I like that idea a lot. Surrounding the bulb in concrete almost completely eliminates the fire risk, and the risk of hot chicken feet. I think it would throw enough heat to take the chill off the coop at night, but not enough to make the chickies heat dependent. As far as the water goes, what if you put hot water in at night before bed? By morning it would be cool, but not frozen. Seems like a simple enough solution. Unless it's Minnesota or something.
What about a smoke detector in the coop? Little chicken fire hats?