Hi Audrey,
Wow, ringing in 2014 at Walt Disney World will be so much fun for you and your family. Keep in mind that this is one of THE busiest times in the parks, but with some careful planning, it can still remain magical and fun. My first and most valuable tip, by far, would be NOT to park hop that day as the parks almost definitely will fill to capacity. Choose which park you would like to celebrate in, get there early and don't leave or you run the risk of not getting back in! In the past, Magic Kingdom, Epcot, and Hollywood Studios all stay open past midnight and all have a special New Years Eve fireworks and shows. Now, the hours and special events have not yet been announced for New Years Eve 2013, but based on years past, you will have tons of fun no matter which park you are in. Last year, DisneyQuest did have a special ticketed event (extra cost of admission) with dance party, confetti drop and party favors, but as I said before, it hasn't been announced for this year, so be on the look out either by checking the
Disney Parks Blog or
Walt Disney World website on a regular basis.
In regards to the decorations, they are usually taken down within the first few days of January and it is an almost overnight change. However, if you are there for the last few days of December, you are most likely to see most of them.
Cheers and happy planning!
~Allison L