@ #6 - I do believe it was found that people who often played violent games were in fact more sensitized to real world violence than the average person. This was found through PTSD research.
But for the life of me I can't find a link for similar studies in google. Too swamped with lame ass-questions and propositions posed by anti-violent gaming proponents.
I'm just summarizing the article:
Mr Rossignol said there was plenty of evidence that gaming violence is "fully processed" as fantasy by gamers. Studies of soldiers on the front line in Iraq showed that being a gamer did not desensitise them to what they witnessed.