Here's a couple of sites to get you started,
French Quarter Festivals Inc., New Orleans - Christmas New Orleans Style - Events and
Jean Lafitte National Historical Park and Preserve - Schedule Of Events (U.S. National Park Service). Check out the Reveillon Dinners on the Christmas New Orleans site and you can check those restaurants out on this site, nomenu.com. I'm not sure about the streetcar running on Christmas day, but here is the RTA site link to the St. Charles line, (takes you through the Garden District),
New Orleans Regional Transit Authority : St. Charles Streetcar Line Update.
Definately get to Christmas in the Oaks and tour at least one of the historic homes in the FQ. If you have your car look into catching a bonfire along the river arround Gramercy, (this guy has pics
Cajun Bonfires Guide Papa Noel AKA Santa Claus Down Into Bayou Country On Christmas Eve.), you really don't need to pay Grayline for that, just a map. Hope this helps; I had fun looking the stuff up and am looking forward to doing one or two of these things myself
PS. just found the link for the bonfires:
http://www.festivalofthebonfires.org/. Also if you're out there get to Laura Plantation it's where Brier Rabbit was born
http://lauraplantation.com/welcome_frame.htm.