My son is the same age and grade, going to public school. Some things they are doing that help us- OT support, books and classes available to parents, speech support(for pragmatic language), after school social skills group, picture schedule and reward system, and an aide if needed. My son rides the bus which gets him to school early enough to meet one on one with a teacher who can help him get organized(avoiding unstructured or unsupervised time). He also leaves the class early at the end of the day which helps avoid more of the chaos. He has social skills goals, including being able to identify pictures of classmates and use their names. He had an amazing teacher last year- she ate lunch with her class most days and was into legos.
We have trouble with birthday parties too. In 2nd grade my son switched teachers halfway through the year. We invited over 40 kids to his party, and only 3 classmates came. Last year, we were invited to 3 parties. One was a halloween party where the parents and kids could come and go and it was great. Another one was for a friend who has his own behavior issues. I spoke to the mom ahead of time and let her know there may be trouble. After seeing how they interacted(the other kids wanted my son to chase them so they could slam doors in his face, and he freaked out when they popped balloons) we chose not to have him spend the night, and both my husband and I stayed at the party even when most parents left. Difficult, but not a disaster. The 3rd party was more focused on the sleepover part, so we didn't go.
Cub scouts has been a good activity for my son. He does better at the small den meetings and has to take a lot of breaks during the larger pack meetings. The best support I have gotten is through parents that I've met through scouts. One mom I met has an older child with Aspergers, and can give me good advice. Her younger son is a good match for a quiet playdate, and is very understanding because of his older brother. Another mom has a younger son with Aspergers, and the one who's my son's age was very protective of him. Another way I met supportive parents was through a bulletin board at the private OT my son went to.
I tried one online support group that didn't work out and I'm still mad about it. It was a group of parents of Aspie kids. They would chat online about how their kids were doing and random stuff(including their sex lives). But ironically they were not tolerant of my social skills- they kicked me out because I did not "talk" enough.
The other online group I joined was groups.yahoo.com/group/dysgraphia/ for parents of kids with handwriting problems, and it has been a great resource.