I agree, that's totally normal. And, in a way and to a greater or lesser degree, we all have to intellectualise how to behave in a social situation. Right from early childhood. And starting with small things like learning bashing another baby over the head with a plastic toy is not appropriate behaviour 
. It just gets more subtle to learn and to teach as we mature.
Creme Really interesting stuff about your DS. My DN has an actual diagnosis of high functioning aspergers. It very clearly comes from my brother (who is 'too old' to have been diagnosed in childhood) DSiL has also worked incredibly hard doing all the stuff you list to ensure he functions as 'normally' as possible. Honestly, the difference in him from early childhood is incredible. Well done for working so hard with your DS. I am incredibly fond of my own DN, but he was bloody hard work before they did all this.
My own mother just closeted DB, wrapped him in cotton wool, and made the problem so much worse. Strangely, my other brother and myself were just left to get on with it, so we kind of brought ourselves up, found our own friends and were out and about playing with our mates. Nature and nurture, a fine line.
Ipsos, from your posts, I see no reason to change my view that your DS is a lovely, energetic, outward going little soul . I think he maybe just needs practise at doing all the social stuff. I was also thinking that, as he's an only child, from a small extended family, that this might be doubly important.