I don't think it always means the same thing. I tend to keep eye contact with people, at least when we are talking. I think it's the facial expressions that happen during the eye contact that will give you clues to what he is thinking.
i genearlly do all those things when I get mesmerized by a girl's look. by that smile he is thinking about your beauty. I also say "f***" and shake my head when I see a very beautiful girl. but just to myself not letting the girl hear it.