We ate there in 2005 before attending MVMCP and yes the characters were in holiday attire. Not sure about the night there is no party but I would think so as the park is decorated for the holiday but I am sure someone else will answer your questions. These boards are great.
Well, for MNSSHP/Halloween they are only dressed up on party nights so my guess is that for MVMCP/Christmas they are only dressed up for the party nights.