There is a lot of info re: Christmas time and New Years Eve in the parks and at WDW.
I would suggest doing a search on here for some info and Check out allearsnet.com
I'm sure some folks who have gone at this time will be a long to help more. We have never gone over the holidays since it can get so crowded.
There is also info in The unofficial guidebook as well as TourguideMike.com that can be helpful with touring at this time of year.