Van Pelt - Involved. There's a reason she has red hair; it's not coincidence.
Bret Stiles - Involved. It's unclear the exact role of Visualize, but there is one. It was revealed that "Red John" or atleast part of the "Red John" identity worked on a Visualize farm. Since Bret founded the organization, he wouldn't fit this mold. He wasn't the kid on the farm. But is Red John one person?
Kristina Frye- Involved. She willingly went with Red John. She will most likely reappear in the final season. Has her insight persuaded Red John in some way? I think it's more than coincidence she has red hair also.
Bob Kirkland- Involved. Before he injects the poison into IV he says that he hopes somebody would ease him of his suffering if he were in that position. This idea of suffering seems to be indoctrinated. Red John is a coward, I don't believe he fully subscribes to his ideaology. Kirkland might be part of the Red John collective, but he is not THE Red John.
Blind Girl- I just read a theory about when Jane scammed the blind girl with the stone. The person didn't make the connection that RJ visited a blind girl.
It's late and I'm sleepy and a bit lazy, so let me get to the gist.
A scene that always stuck out is when Jane kills who he believes is RJ. That man knew details about his family only the killer would know. I doubt someone would be debriefed to remember that minute of details. Maybe the killings are ceremonies in which many people partake.
I believe all seven names on the list are associated with Red John. RJ was able to realize how far Jane could deduce with Kirkland's research (or maybe Kirkland for/as RJ, but that's not important). The concept of suffering is paramount to Red John. That's how he rationalizes what he does. Suffering heals. It has to do with balance read the poem RJ recited http://www.eecs.harvard.edu/~keith/poems/tyger.html
Hopefully this sparked ideas.
This is a good profile of Red John btw: http://thementalist.wikia.com/wiki/Red_John