Thank you, the index cards and taking a full length photo are very helpful ideas. If the CM won't be able to keep the flyer would it be okay for me to show it to him/her or will they not want to look at it? Is the GAC really that helpful to have? I have used TGM, TP, and RideMax to make some good plans and we will use FP's, go early, etc. I had something like the GAC when we went to DL 4 yrs. ago and we were allowed to go through the exits to many of the rides. I don't think they had FP back then. I have read all the info. and it sounds like this is not quite the same anymore. It seems that DW has a written policy that you do not need flyers or doctor's notes yet it seems a bit subjective based on who you encounter at Guest services. I guess the best thing is to come prepared, have a plan, don't shoot for the moon, but hope for the best, and be happy no matter what!
The information about GACs in the disABILITIES FAQs thread that Cheshire Figment pointed you to is the best information to use. The Americans with Disabilities Act is what says that WDW can't require a doctor's note or any proof of disability.
If you are able to explain your child's needs, you will get assistance with meeting the needs. It is not meant to shorten your wait in line, but to provide assistance that will meet the needs.
Many people have found that using TGM (Tour Guide Mike), Fastpasses and going early are actually more helpful than a GAC.
The GAC will only help in lines/attractions to give you a more appropriate place to wait. And, your experience may be different, even on the same attraction on the same day at a different time. Some of the things that affect that are how busy it is, staffing and how many other people with special needs are there at the same time as you are. You won't know that until you are in line.
Getting Fastpasses will generally mean that you will be getting on an attraction within 10 minutes of entering the line. It is a more consistent way to get into attractions than using a GAC is.
TGM and getting to the park early are helpful because they put you in the parks when they are not that busy. That not only helps with waiting for attractions, but also means the parks are less busy and less overwhelming/stimulating to many people with special needs.
Even during busy times, like Easter, it is possible to go on all the attractions in Fantasyland (for example) before 10:30 am without more than a 10 minute wait if you get to the park early.
You can use your flyer to help you to talk to the Guest Relations CMs about your son, but they will not want to keep the flyer and it would not be useful for them to have it in case he bolts on you; it would not be available to people who are looking for him.
It would be better to take a picture on your cell phone or digital camera each day to have a current picture. If you want to use the flyer, keep it with you so that if he gets away from you it is available to show to CMs at the time.
Also, if you have not read them, there are some links to past posts in post #3 of the disABILITIES FAQs thread. Several are about travel to WDW with someone with autism.