The identity of the witch in the dunk tank is never revealed. However, given her voice, it is a very strong possibility that it is meant to be the Mrs. Bennett teacher character that was featured prominently in Season One.
Jamie's last name, White, is revealed in this episode.
Linda Griffin (Sandi's mom) says that one of her boys is named "Chris." This would mean that his full name is Chris Griffin, also the name of a character on Family Guy (though obviously predating that show).