We were at MNSSHP in 2004. It was Food & Wine and Golf tournament time. The parks overall were a bit more crowded than we are used to (always go offseason) due to the Hurricanes plus the locals on the weekend at the
F & W. However, we didn't really have any problems at the parks, using Fastpass when necessary. I didn't notice any mosquito problem in Oct 2004, but you can never tell with Florida.
MNSHHP is really fun. You can get into the park at 4 p.m. with your ticket. We didn't use a park day on the day we went. We were at the gates before 4 and waited to be let in. We rode a few rides, DH got his hair cut and decorated for the party and then we went to LTT for dinner. It's cool. They had storytelling in the foyer before the party. We actually finished before the party began and walked around Frontierland with NO ONE around. Pretty cool!