First of all, my condolences to you. Part of your trip success depends on how laid back your group will be with crowds. Accept it'll be a madhouse before you leave and you'll have a good headstart.
Regardless of park, a technique that works well is to either go rope drop early and/or close the park. I'd be outta any park by 11-12 latest and would show up again only 2-3 hours before closing. This should minimize your exposure to the maddening crowds. The problem with this strategy is phased closings. Guess it depends on how badly you need to experience the fireworks in the parks.
NYE is a crapshoot no matter what though.
- Epcot is scheduled to be open until 1a on New Year’s Eve
- Disney’s Hollywood Studios until midnight for the general public, and 2a for Walt Disney World Resort hotel guests
- Magic Kingdom is currently scheduled to be open until 1a, but likely will be open until 2a
- The Magic Kingdom has Wishes at 8.30p and special New Year’s Eve fireworks at 11.50p
- Epcot has its Illuminations fireworks show at 6.30p and 11.40p, plus DJs in various pavilions.
- Disney’s Hollywood Studios will have fireworks at midnight
I've heard DHS has the best NYE fireworks but I think Epcot has a larger area to disperse people and seem less crowded.