I may be brain dead this afternoon and if so ignore me...But, I've read your post three times and I haven't come away with the specific stuff he's doing that seems immature. Everything you described for me sounds pretty standard behavior for many four year old boys. A lot of kids that age don't really have tons of friends and don't necessarily play well with strangers. If he has a couple of kids he will run around and play with that sounds fairly good to me.

Does he go to preschool?