Hi D.,
I am going through a similar situation as you this year and have been experiencing similar feelings and apprehension and fear. What I plan on doing, to try to start the school year off right for my son and I, is create a booklet that is all about my son -- a really quick read with pictures of him that will hopefully give his teachers and the administrators at his new school some information about our son's history, his likes, his hopes and dreams for the future, my husband and mine's hopes and dreams for his future, his strengths and weaknesses, etc. This booklet is based upon the MAPS (Making Action Plans) concept that you can read about in the following links: http://www.allenshea.com/maps.html and http://cecp.air.org/_discstrength/00000030.htm
The purpose of this booklet is to get my sons new teacher and the school administration thinking in terms of the fact that my son is more than just his "autism" or "special ed" label and to get them familiar with his strengths (fun-loving, loves reading, spelling and music) and weaknesses (doesn't know how to initiate friendships/interactions with his peers yet), and what he needs from them to succeed in school (don't dumb him down because he is an IEP kid, set him up with some peer buddies in class to help him transition through the day).
My son is going into kindergarten so I am creating it in a picture book fashion but, since our son is older (if you do decide to do something like this), you may want it to be set forth in a 1-page format with a picture of him somewhere on there and make it a quick read. Ask that the document be placed in your son's confidential school file and that a copy of it be distributed to all school personell who will be working with him throughout the school year.
Also, I know it is hard but stay positive. Negative feelings feed off of negative feelings. If you are spirituation, you may want to put that practice to use right now so that you can approach the school year from a place of peace and understanding. I've learned the hard way that when you approach things with fear and apprehension in your heart, other people react off that and it can make for a disasterous situation.
You may also want to start building connections with the PTA and getting to know other parents who have children with ASD, Aspergers and such, who are or have attended the same school so that you can draw up their experiences to help you and your son navigate through this new school experience.
Best of luck to you and your son. And remember, stay positive and proactive!
L.