Thanks all! I really appreciate all of this advice.
So, based on everything I've seen / read, I think we're in good shape as far as nothing getting frozen when we have electricity. We've have several days this winter where we hit -20C, and the basement never really got below 9C (nor did any other room) with just the heat pump running upstairs at 17C overnight. I was looking at where all the pipes run, and everything (including the basement) is inside the insulation envelope. The two hose bibs run through it, but I always turn those off in the late fall. There's one exception -- there's something heading out through the insulation in the basement, but it's in a region where we don't have any plumbing above it. I have no idea what it is, but it hasn't been a problem thus far (2 winters in). My intention is to have a plumber take a look whenever we have one out for something.
My pellet stoves draw is ~330W during ignition (say ~20 minutes) and then about 100W to run after that. I've seen the idea of using the deep cycle batteries and a sine wave inverter, and I kind of like it. I did a bit of googling about the standby generators and battery backups, and I wasn't overwhelmed by the cost-benefit of either one. Perhaps a simple gas generator is the way to go (I could run in through the UPS so the output is a sinewave). I don't love the idea of having to leave a window / door cracked open, and having to store / stabilize gas, but I suppose I could do it.
And I've talked to a few of my neighbors. 1 has a wood stove, another has a generator (but has never taken it out of the box) and a third plans to turn off their water and stay with their in-laws. No one does anything to protect their pipes on cold days when the electricity is on. As newcomers (and immigrants) we don't have any family nearby, nor friends that I'd be comfortable imposing on. At the same time, we can certainly afford a hotel.
And I don't think long power outages are frequent at all. We had 3 nor'easters this winter, plus a big ice storm, and we lost power for 2 minutes. However, if the ice storm hits just right, you can be without power for 3 or 4 days. I think that last happened 7 or 8 years ago, and I'm not sure how long it had been before that. Honestly, given the infrequency, I think I'm leaning towards toughing it out for 24 hours, then winterizing the house (drain the pipes, pour in antifreeze) and going to a hotel (or at least sending my wife and daughter there). If we go through this once, though, I may revisit my plan and hopefully battery backup technology will be a bit better by then. :)