Yeah I drove in and around Boston for like five years. Pittsburgh driving is downright relaxing in comparison, although their are some... interesting design choices here.

Yes.

If you burn hydrogen in pure oxygen you won't get any, but typically we burn things in air. Air is about 78% nitrogen, and even though N2 is pretty damn unreactive when you have so much of it hanging around in a hot flame, some of it will get oxidized. The hotter the flame, the more you get (and hydrogen burns very hot).

My understanding is that you can burn H2 with about 2x the theoretically required amount of air to reduce the amount of NOx emitted to basically nothing, but that's also going to reduce the efficiency of your boiler, so it's a tradeoff.