F! is not subject to quite as many wind cancellations as the fireworks but it can happen.
I don't believe you "get" anything if the show is cancelled. That is clearly stated in the booking terms. We had F! stop about 5 minutes into the show last time we did Hungry Bear and they came on and announced the show would not resume. We were not offered anything (nor did we expect anything). I realize that's not exactly the same but...
We have BB Fantasmic! lunch booked for Sunday so I'll be interested to see if we at least get the seat cushions if the show is cancelled... I have two already but we find them very useful and are hoping to get two more.