The cool thing about Magical Gatherings is that is simply coordinates all your reservations, priority seatings, tours, events, etc. It does not change anything (rates, codes, deposits, etc.).
So, we have room-only reservations through CRO under several different rates (FL resident, SOG, and Operation Salute) and the deposit rules are the same that they've always been for room-only ressies....one night down with the balance paid at check-in. Priority seatings....just the usual deposit at CRT. Candlelight Processional we had to pay in advance like everyone does.
The only thing different for groups is that when you make group PS, if you don't cancel or change the number in your party 24 hours out, you will be charged a cancellation fee (I think $10 per head, but don't quote me on that). But that's always been the group dining policy; that is not new with Magical Gatherings. (Just so you know, you don't have to call group reservations until you have 13 people.)
As for the Magical Fireworks Voyage and the other special new experiences (International Storybook Dinner at Epcot, Good Morning Gathering at MK, and Safari Celebration at AK), they require payment in full 45 days out. Cancellations may be made up to 6 days out for refund. No cancellations within 5 days of event.
HTH. Let me know if you have any other questions!
Katie