Disneyland IS open christmas day... they are open 365 days a year! As for your other questions i cant tell you because i dont know... But when i get back (leaving in 3 days) Ill let you know
DL is pretty busy on Christmas Day - a lot of people trying out their APs or just going to the parks for Christmas.
I'm sure you'll have fun there despite all the crowd. Just make sure you use the fastpass system, and hit the Holiday special attractions: Haunted Mansion & It's a Small World early in the day because even the fastpass lines are too long in the evening. (But, make sure you see the Small World facade at night - it's spectacular )
I am going to be there on christmas day and expect it to be VERY BUSY. I made all my ressies, Blue Bayou, Goofy's kitchen, and Avalon cove. I normally am a militant, do or die disney die hard but I think that this time I am just going to relax and take it easy. just hope to go on indiana jones atleast once