I see getting home as the big problem. I do not think that 20+ miles is easily doable anything but the best of conditions. Are you/wife in good enough shape? Are you used to walking long distances or will you end up disabled by simple blisters? Consider that 20 miles at 3 miles an hour is 6 and 2/3 hours of straight walking: no pit stops, no breaks, no delays. In a really bad situation it could stretch out more, and I think easily end up catching you outside at night, turning it into an "overnight".

So, anything to speed the journey, e.g. bikes, is good. Have enough in your kits for an overnight somewhere while getting home.

This brings up the question of friendly "way stations" in Brooklyn (which I assume you would be passing through). Are there friends/relatives or just places where you could stop and rest and re-supply or pick up additional supplies? Or how about, if you could walk to you old home in Brooklyn, could you stash bikes/mo-peds somewhere in Brooklyn and walk there, then ride the rest of the way? If not with friends/relatives, how about a self-store unit with 24 hour access?

As far a the new house location goes, generator and water are pretty well covered, and your right about the hurricane=bug out. I grew up on the south shore of Long Island, and were always ready to leave. But if it is only a hurricane, even with 20 feet of water over your house, it won't cover all of Long Island. The North Shore is much higher than the South Shore. Consider a temporary bug out just across Long Island to someplace on the North Shore; again, relatives? friends? work associates?

As for your number 3, what else should I worry about, I feel strange mentioning this to someone from Brooklyn, but crime? Not home invasion stuff, but simple B&E. In many suburban bedroom communities, the high time for homes to be robbed is 10am to 2 pm. Everyone is at work/school etc. and no one is around; a ghost town. Consider a good alarm system, even with your au pair there full time

Just a few ideas I hope you find useful