When I made our ressies for this for Dec 22, I was told that we could each bring drinks such as a cocktail, etc. My thought for the X-massy feel though was mugs of hot cocoa. I know we certainly went through a lot of it when at the World last December. Leave to us to be there during record FL cold but hey, it was still 40+ degrees warmer than at home at the same time. Still hoping it's a little warmer this year though.
Also it doesn't seem to matter if you call WDW-PLAY or DINE. I called PLAY to ask some questions about this when I hit my 90+10 booking window and was able to actually make the dining ressies on the same call. I called -DINE about a week later to add another ADR and was able to do that and book the carriage ride.