So I called DVC member services-- she told me she sees fireworks scheduled for every night except the 22nd. But suggested I call the dining line because that's where I made the reservation.
So I called the DWD-DINE line-- the CM tried to tell me that F! was still going on that night and it was the same thing as the fireworks. He had no idea what I was asking.
So I chatted with a CM on the Disney site who assured me that if I have a ticket, I will have the full event.
My bigger concern is that Disney will cancel the Frozen stuff without ample time for me to arrange my plans. Because I have 6 year old Frozen addict, so it's kind of a big deal here.
And I am now 100% convinced that the DIS is the only helpline I need to properly plan a WDW vacation, because the guys on the other end of the Disney lines seem to be the last to know sometimes (which is so not fair to them). I really can't thank you all enough for the time you take to answer questions that could not be sufficiently answered elsewhere!