Howdy All--US DISer lurking on the Canadian Board. Allow me to help a bit.
MLK day is in January--January 17, 2005 to be exact. We were actually at WDW last year over this week, and the crowds were up quite a bit over that weekend, but by Tuesday, many of the Fastpass machines were covered, and we never waited longer than 15 minutes for anything.
President's Day is in February--February 21, 2005 to be exact. This is also the Monday that starts "Winter Break" or February School Vacation for many of us who live in the North East. I would expect it to be moderately crowded. We are actually heading to the Ft. Myers area this week, as WDW was not in the cards this year.
I can't help at all with the cheerleading questions, sorry.
Hope this helps a bit
Debbie