I for one think the Pasternoster crew are a blight on the show really. Hate 'em. Shame, since they were good in their first few appearances.
Also: Santa is an interesting one, because they won't be able to have the Doctor play it like Robin Hood; the Doctor can't deny his existance on Christmas day at prime time with tons of kids who still believe watching... so I'll be interested to see how it handles that bit.
One of the best lines Moffat ever wrote was about him, mind: "Look at you, bouncing about, you're like Father Christmas! // Who says I'm not? Red bicycle when you were twelve. // *Rose looks dumbfounded*)
Don't forget that in A Christmas Carol, the Doctor referenced knowing Santa Claus down to a photo with him, Santa and Frank Sinatra if memory serves...or was it Einstein? He even called Santa Claus "Jeff". I do wonder if Moffat will continue that