Looking it up, self inserts look to generally be as minor characters, http://en.wikipedia.org/wiki/Self-insertion. A lot of people tend to consider self inserts to be pretty much the same as being a Mary Sue, but it's really not.
Can main characters be self-inserts?
Also, are author surrogates necessarily the same as Mary Sues? You see, in my story, I have a number of people in my cast of characters, and I'm simply trying to avoid any possible Mary Sues. I can't really use the test, though, 'cause I haven't finished the story yet, and I think some of the questions on the quizzes are related to the plot, of which I haven't really settled on yet.