The only scheduled event is the "Mickey's Trick or Treat on the Street" procession. It starts an hour before the party ends (i.e. 9:30 or 10:30) over by Paradise Pier, and ends at Candy Corn Acres (aka Sunshine Plaza). It stops twice for two short performances - in front of Golden Screams and at Candy Corn Acres. We saw it Friday - it got to Candy Corn Acres about 30-35 minutes after it started, and the performance thing was 10 minutes or so. If you want to be in the front row at Candy Corn Acres you need to get there at least 15 minutes before the parade starts at Paradise Pier - though yes, that means you'll be sitting/standing around for 45 minutes or so.
There are crafts and games for the kids at Pirate's Wharf, and dancing at the three party spots. The Boardwalk games are open, and they are free - everyone gets candy for participating.
There's lots of character meet and greet - several formal spots, where the lines tend to be pretty long, but there's also lots of characters just walking around the park, and there are usually no lines to see them. There's also characters dancing with guests at each of the party spots.