To answer some questions:

-It goes out about every month or a couple times a month. It last anywhere from an hour, a day or two, or in the winter is typically longer 3-5 was average but like last Thanksgiving when we had 3 feet of snow and below freezing temps, it was out 9 days.
-Their heat is primary water base board lower floors or electric base board on the upper floors.
-I don't know about a subsidy but will have to look into that.

-Cost benefit analysis is great idea. I will work this up immediately.

-The type of generators am looking at come on within 60 seconds of the power going out. The folks or I have to do nothing and nothing when the power comes on, it shuts off automatically returning to original source of power.
I was thinking whole house (16kw generator) as opposed to the one that runs select things (11kw) because it is a difference in price of $550. Then for the upper floors there would be lighting (no worry about groping/walking in the dark for flashlights), heat up there to not just the first floor, and an oven, which would not have with the 11kw one for, in the scheme of things, not much difference.
-We are on a well so yes, there is no water for toiletries or drinking without the power.
-Both heating systems that control different parts of the house need power to run.
-It did not occur to me about the tax credit.... will look into that as well.

Great thoughts everyone! I have some work to do. Thank you! Let you know how it goes.