it's definitely Bob kirkland because he's the one who broke into jane's place to get pictures of the scheme jane mad to find who is RJ. there is no way RJ could know the list jane made except if he had all the clues jane had. besides Bob told Lisbon once that he had a circus life and that he considered himself an american for travelling everywhere with his family. and that is a leek to find out how he could know about jane's happy memory back then.
I am not sure who RED JOHN is but I very sure that HE is NOT KRISTINA FRYE. WATCH the last episode in SEASON 2 - Red Sky In The Morning.
In the event where PJ was saved by Red John from the two insane students, you can listen to his voice. Though RJ may sound feminine, he definitely sounds like a MAN. Now when he mentioned "Roll Tide", which in the event was the one that Kristina Frye said to the waiter in the start of the show, it was actually because HE WAS LISTENING TO THEM WHILE THEY WERE DATING. Look closely at the scene and shots when PJ and KF were talking to the waiter, during the time before she mentioned "Roll Tide", you can see a man wearing a black suit on the table next to them. He has black straight hair. You would see that in the left side of the screen, near Jane. He was actually interested in ROLL TIDE because the waiter mentioned the phrase "CRIMSON Tide" where his uncle belonged to. CRIMSON, a shade of RED. You can check the episode, see for yourself. Kristina Frye is not RED JOHN.