Hi! I'm in the northeast, so different area but similar winters. I would highly recommend NOT heating your coop. Chickens are surprisingly hardy, and slowly adjust to low temps during the fall and winter. If, however, you have a heat lamp, they won't adjust...and if the power ever went out (as it often does in snowstorms), your birds won't stand a chance. Of course, there's also the risk of fire with heat lamps. (If you're absolutely set on heating the coop, I've heard the Sweeter Heater is the safest option.)
That being said, there are some things you can do to help. Make sure there are NO DRAFTS blowing on the birds, but that there is VENTILATION up above the heads of roosting chickies. People here on BYC recommend either 1 square foot of ventilation per 10 square feet of floor space, or 1 square foot of ventilation per bird. The former is the minimum you want for winter, and the latter more of what you want for summer. It's great to have vents/windows that open and close so you can control the amount of ventilation.
If you have a run, I'd also recommend covering three or three-and-a-half sides of it with a clear tarp or plastic sheeting to block some of the wind (
http://www.thegardencoop.com/blog/2011/11/25/chicken-coop-plastic-wrap-winter/).
The Deep Litter Method can also generate heat in your coop during the winter. Here's a good article on that:
http://www.the-chicken-chick.com/2013/10/the-deep-litter-method-of-waste.html. It's especially important to have good ventilation if you do deep litter.
As far as heating the waterer, I use a nipple waterer as well. Is yours a bucket, or a more sophisticated design like the Chicken Fountain? If you have a brand name or a pic, I can help you more. In general, many report success using the API 250-D 200-watt heater, sold on
Amazon, in their nipple waterers. This is my first year with chicks, so I can't tell you if it worked for me...sometimes the vertical nipples will still freeze even with a heater like that. Personally, I think I'm going to buy the Cozy Hen waterer for my three chicks this winter...15 watt vs. 200 watt makes a big difference in the electricity bill!
One last bit of advice. If you have any room in your coop, I'd move the waterer inside for the winter. The coop is generally a bit warmer and certainly more sheltered than outside, and unless you have a roofed run, some chickens won't like venturing out in the snow.
Hope that helped!