Hi Cindy,
How fun that you are going to be at
Mickey's Backyard Barbeque on Halloween Night! The Disney Parks Blog just featured a post on this yesterday - click
here.
I'd plan to arrive a little early. After you've checked in at the Fort Wilderness Pavilion, they typically have a character there for a photo op. They will sign autographs at that time. The characters may rotate so keep an eye out.
Once the show begins, the characters come out on the dance floor to dance and mingle with guests. There is a large dance floor in the center of the pavilion and two smaller ones on each side. The characters don't typically stop and pose for pictures or sign autographs but the action shots are priceless.
During the breaks, be sure to check outside the pavilion (towards the side where the hostess stand was when you first checked in). I've seen the characters come back there to pose for pictures and sign autographs. We've also been able to catch Mickey & Minnie there at the end of the evening for one last photo as we're heading out.
Wishing you minnie magical spooktacular memories :-) Allison