Need help with finding the right generator?

I am looking for a generator as we have had two black outs in the past two years. One went almost 3 weeks. I would like it to be able to run the boiler, fridge, stove, tv and a few lights...Don't need to light the neighborhood. I only need to get by without being too uncomfortable. Area is about 14,000 sq feet. Can someone tell me what size I would need? Also, how do you hook up a natural gas generator? I hear it's cheaper to run. Thanks, Linda