I just went to one of these and it was adorable! I can email you photos if you like! My sis is a professional clown, and I assist her and do the face painting, so it was tons of fun for the kids.
Anyways, she had corn dogs, cotton candy in cute bags as the party favors that she gave out as the children were leaving. Then, in tall glass jars, she had colorful candies, like licorice, m&m's, veggie tray and fruit kabobs. Those large pretzels with nacho sauce to dip in would be good.
For games, you can do bobbing for apples, pin the tail on the donkey (or nose on the clown or whatever).
Prizes, the little bubbles, or little play-dohs or those glow stick bracelets would be cute.