I don't know anything about the photopass, but I can tell you what I know about the parks on NYE.
First, I have not been to MK on NYE, but I have been to EPCOT. I would also recommend EPCOT having never been to MK to see what they do for the holiday. In EPCOT, they celebrate New Years for each country in WS. They shine a light and highlight each country as they're actually hitting midnight. Each country gets a musical tribute of sorts and their own fireworks spectacular. Then, they have on final massive New Years fireworks show. Seeing the individual countries as it was New Years for them made it really special and fun to watch.