We went to the first weekend last year and yeah, it was a wait to get the autographs from Anthony Daniels and Billy Dee Williams, but once Disney got its act together and actually handed out the wristbands, we were fine. There were 2 sessions for autographs and they gave out 60 or so bands for each person for each session. I believe they took about 10 standby people for Anthony and about 15 for Billy Dee total on the first day. The trivia signup went fast (limited to about 30 people). The worst wait was in Tatooine Traders. Waited 1.5 hours to check out. Did not even try for pins or coins that first day. Went during EE on Saturday and got the pins, coins, etc. with absolutely no wait. The busiest thing was the WWTBAM since there were most of the star wars guests and then regular people who did not realize that there were star wars only editions. Those filled up pretty quick but were awesome (I actually got on the board for that one, which is really good since I don't do the books or expanded universe).
I would say that in a day and a half, you can do everything if you are devoting your time to the star wars events and ignoring everything else. The last event ocurrs around 6:00 at night, so you do get some park time as well.
Once the list of celebrities gets released, I would check with your son to see if he really wants those autographs. I would say that our Billy Dee wait was a waste of time - he really is not a personable man. Anthony Daniels, on the other hand was awesome! He took the time to chat with everyone. However, this took a good chunk of our day (45 minute wait until they gave out the wristbands, 20 minute wait at the first session, 30 minute wait at the second session (we purposely came late since we had the last bands).
Sorry this is so long, but can you tell that I am a fan and really enjoyed the weekend?