Hi! You can go to guest relations and obtain a guest assistance pass (tell them you have a child with special needs). This will be able to help with the lines. If you are staying on the property take advantage of the early/late hours. It may help. Get/Take a stroller. Do the parks in spurts so as not to overwhelm your child.
There are many more people on this board that may be more of help. But, overall, people have had positive experiences. Just go with the flow and let your child guide you.
Best of Luck!
Kathy