Hi Clara. Hope you don't mind my "butting in"... I don't have anything concretely useful to add, being so far removed from the US system and not having begun to tackle these school issues yet, but I just wanted to say that some - not all but some - of what you say about your boy reminded me of my son. He is also not classically autistic and yet shares some of the traits, I think. He doesn't have the Obsessive Compulsive Disorder (OCD) or black and white thinking, for example, but there are social situations he just does not "get". Is constantly crossing boundaries that his peers have long since assimilated and respect... is a bit like a bull in a china shop often. Will run into people's houses or property with absolutely no sense that he should not do that, shouts out rude things about people (well, not often, but occasionally) that seem typical of a much younger child. Is also very sensitive and highly emotional, as you describe (though perhaps less clearly anxious). Gets on well enough with children and knows how to play and share but there are always a higher level of quarrels and difficulties around him than there are around other children. I don't think he really understands that he has to show an interest in others - he just tries to "fascinate and compel" others with his dazzling personality...
Could not all of this be covered by a diagnosis of Pervasive Developmental Disorder (PDD)? My son doesn't have any diagnosis yet (though frankly he is to me like a textbook ADHD, at least) though I have wondered if he fits the criteria for Pervasive Developmental Disorder (PDD).
Anyway, like I say, I'm sorry this is not of specific help to you other than to know that other kids also don't seem to fit the specific box of autism and yet... something is not right socially, there is some skills they just don't have that allow them to fit seamlessly into life.