tarheelalum --
You did the right thing by just jumping in and asking the question! I even have a section on page 1 titled "You Don't Have to Read the Whole Thread," but I think that people still feel that's what they're supposed to do!

There is a Search feature for each thread, and if you ever want to find specific mentions of something, just type in a keyword or whatever you're looking for, such as "traffic," or "Christmas day," etc. I find that the Search Thread feature is often is more effective and specific than the Search feature for the whole board.
From all that I have established from reading various reports, Christmas Day may start off reasonably quiet in the parks -- not empty, but manageable. By mid-day on 12/25, or by the late afternoon, the crowds begin to really kick in, and then the next few days should be very crowded. The rumored
Frozen invasion of Hollywood Land is supposed to begin on 12/20 (
if the rumors are true), so that will impact crowds even further in that post-Christmas week.
If there is rain, or even a threat of rain, that will scare a lot of people away and the crowds will drop off considerably.
In
this post, you will find Trip Reviews/Reports. Under the
2013 section,
Bret/mvf-m11c's TR from post-Christmas/pre-New Year's is there, and in the
2012 section you will find reviews from
JediMasterNerd and
Mickey&JoshNut, who were at DLR over Christmas and beyond. All of those recaps/reports will give you an idea of crowds.
The hours will be as long as they can be in both parks. I think that there is a good chance of both parks being open for EMH every day between Christmas and New Year's, instead of just one park or the other. Here is what the hours looked like in
December 2013.
As for traffic -- I've never traveled up from San Diego to DLR on Christmas Day, nor have I even traveled from where I am in L.A. to
Disneyland on Christmas Day. But I
can tell you that the streets around my area of town -- and I live in a pretty active, bustling area of the city -- are nearly empty for hours on 12/25. It's that way on New Year's Day too. So I am going to guess that your idea of the traffic being light is spot on -- a lot of folks will be at home, enjoying the day with their families.