Generally...
No
MVMCP, but you should still have the Christmas parade at MK during the day.
Festival of the Holidays at Epcot runs thru 12/30.
Decorations will still be up at the parks and resorts.
Expect shoulder-to-shoulder crowds. We went to Universal/Diagon Alley one year on 12/26 and had to leave; I was starting to have a panic attack due to the crowds, and I don't EVER have panic attacks. Disney (Epcot) on 12/24 was not as bad, but really close. We had a CP breakfast package, spent the day at AK, hopped to Epcot in the late afternoon.
Good luck with dining on NYE. You'll have better luck with resort and Disney Springs restaurants, but not sure you want to leave the parks.
MK and Epcot have reached capacity on NYE. I'd recommend going early and being prepared to stay for the duration.
If you are thinking of going to the Poly to watch the fireworks, unless you are staying there, they won't let you on to the beach... or at least that's what's happened for the past couple of years.
Resort/hotel prices will be the highest of the year- as will the crowds- and no discounts. I'd put my money into the cheapest onsite hotel and use the savings towards LL passes.