The fast passes are ONLY for actors, not for the characters. (these people are not in costume - when I was there last year, the guy that played Chewbacca was there along with one of the Trade Federation head guys). You will find regular characters willing to do pictures and or autographs all over the park, but mostly seem to be in two areas. One is by Star Tours and Tantooine Traders. In this general area, there were 3 or 4 fixed signing posts (popular characters like Jedi {had my picture made with Mace and Kit Fisto}, Chewy, Boba Fett, Ewoks, etc.) Also down the way towards WWTBAM, we had our picture taken with Clone Troopers, an ARC Trooper, Princess Amidala (who signed autographs), had Jawas wanting to trade a lunch box for my earings, etc. You will also have a chance to have your photo taken with Jedi Mickey in the normal place where Sorcerer's apprectice Mickey is posted at MGM.
If you like the characters, don't miss the Star Wars parade (different from the Stars and Cars parade) and make sure you hang out in those two general areas. So many other characters were simply roamining around. Several bounty hunters, both clone and storm troopers, a Gemorrian Guard, the cantina band was playing at times, Greedo, even the Emperor made his way through the crowds with his royal red guard.
They also do the Jedi Acadamy where younger children (up to 10-12 I would say) are picked from the crowd, taught a series of moves and then *que DV's theme* both Darth Maul and Darth Vader come out and each child gets to do those moves against one or the other (depending on if you are on the top stage or the bottom area for your training). The kids LOVED it.
There were Storm Troopers on top of the entrance to MGM and we had the thrill of my young son's life when one came down off a lift as we stood there watching and came over and stared my son (who was brandishing his Jango gun) down for about 30 seconds. He was totally enthralled!!!
It is an amazing site!