If Ben is to play Obi-Wan in the original trilogy, then him switching to Leia makes the most sense - she is the one who joins the main party as it is when he dies. Then again, she is the first main character to pop up, so I guess her being a PC from the start makes a certain amount of sense. Of course, who's to say that we won't get some new players somewhere along the line?
I am still fairly sure of my own theories regarding Annie and the GM, of course.