As far as audition requirements go, they are generally as follows:
"Pianists should prepare three memorized pieces. One from the Baroque era, one from the Romantic era or 20th century and a movement of a Classical sonata (Haydn, Mozart or Beethoven)."
I suppose I could rework K309, but I'd love to play something else, I love music from the baroque to 20th century, and would have no qualms with learning a new piece. As far as the course goes, I'd probably just audition as a freshman in regards to applied piano lessons goes. I only did one semester of "pre-college" piano and one semester as a freshman at the community college although I played the pieces I listed above. In terms of other music though I've taken two years of theory, ear training, and three semesters of music history so I'm not really worrying about those.