1. I always try to book travel with the idea it might not happen. I don't typically buy
trip insurance, but I usually opt for refundable hotel rates over non-refundable ones. Even at WDW, I often choose 'room only' reservations over packages, unless the package offers an exceptional discount.
2. I also ALWAYS try to keep in my head that it might not happen, in the sense of keeping my expectations low. It sounds like you also had the idea that a hurricane might intrude upon your plans. In a way, you might say a hurricane has happened. We semi-jokingly say things like, "If we were to take a hypothetical trip this summer, where would we want to stay?" not to the point f being annoying, but just to enough to keep options open.
3. In the case of non refundable flights, I don't think I'd fully cancel. I think I'd just restructure it a little. In practice, I've only rarely fully cancelled a trip, but I have restructured many. I keep what we want and re-do the rest. Depending on the terms of your WDW booking- you may well be able to cut your RPC days in half, and stay somewhere else instead.
FL has MANY options. I'll start close: another WDW hotel, a Universal CL (or non CL) room, a high end non-theme park hotel, a day at Cape Canaveral, St. Augustine, Tampa, Clearwater, or head south to see the Everglades or one of FL's MANY other natural parks. Each of those locations offers some really unique stuff to explore. Pick what appeals to you those days.
If you just want to spend a non-theme park day relaxing at a very nice hotel pool, the Orlando area has many options. If the proximity would be too close, there's no shortage of opulent options all over FL.
4. Instead of expressly planning FP/ADR's to get, we usually play a game, A or B. It is very simple: I say two things, "Peter Pan or Pooh?" If Pooh wins, I'll say, "Pooh, or Escape From Gringotts?" and so on...It is pretty fun! I later use the answers to pick FP, ADR's, and even WDW vs. US vs. another city. Maybe try this game, and see where everyone in your family has their heart.