Defensiveness and Misunderstanding

(A) He has a hard time recognizing people and relies on their voices to determine who they are, and what their intentions/moods are. I have noticed that older kids and adults will often give verbal warning of their approach by saying something like "Hey DS, what are you playing with?" etc, whereas children his own age, and younger, tend not to do this. Could this have something to do with it?

(B) He also has that "bull in the china shop" thing going on. It is his standard MO that he will attempt to engage with a child and end up accidentally hurting them while hugging, throwing a ball, etc and the child either reacts aggressively, or defensively towards him in return. Or the child will cry, and then he gets into trouble. Could he be realizing that he often makes mistakes that land him in time out, so these interactions are becoming a source of stress?

He has taken to preemptively protecting himself and his things when other children are around the house, or at therapy, and when he comes home from school he is saying that ALL of the other kids are bad/mean. Its PreK, I am sure some are, but most of them are not. However, he is getting sad faces in class for aggression (biting/pushing), but when asked what happened, he gives me the impression that he was trying to interact with these kids in a nice or helpful way and something went awry. 

Once he said it was that he was trying to show a girl that the teacher said to use the green color and she wouldn't respond...which somehow ended with him getting frustrated and biting. Another time, he tried to hug a girl, and accidentally poked her in the eye. She started crying, landing him in time out. His OT was telling me last week that a boy in the sensory gym approached him while playing a game, picked up a game piece, looked at it, and then left. She said that DS responded by yelling and telling him not to take his game away, when she said it was pretty obvious that was not the other child's intention. Ordinarily, I would think that he were lying, or just being a 4 year old only child, however, I have seen him engage in similar behavioral misunderstandings with younger cousins and friends in the neighborhood. These misunderstandings appear to be causing him stress, and to always have his guard up in these types of social situations. Has anyone dealt with this before? How should we handle it?