4th of July performance will be announced in mid to late November. Sometimes another special show will be announced at that time as well, such as last year Hugh Jackman. Then the full schedule is announced around the 2nd week of February.
I'm not sure Criss is the right "type" for Dewey at all. He's supposed to look a little scruffy, a little unkempt, a little washed-up...which makes his ultimate success with the kids' rock band so satisfying. I'd kill to see Jack Black reprise the part, although he may not have the physical energy to do it live.