I think Chopin ballades are Scherzo's are the perfect solution to every 20 minute audition. They are shortish, and full of amazing music, and technically challenging. Bach preludes and fugues are always good. Chopin etudes are always risky. I'd go with a Liszt concert etude, or a Debussy etude, or summit a little easier to pull off, but with enough technical challenges in to show off.
I know people who played Dante for their auditions and they got in. They probably will stop you though.
For all my auditions I played Chopin scherzo no3, Beethoven appasionata and Liszt concert etudes.
The scherzo is perfect to start with, you sit down..drop the stool (easy for me I always sit very low...usually stools don't go low enough so I need a seat, but since I couldn't ask for a seat, a stool had to do so I just put it to the bottom) and BANG! Your in with that amazing opening. Easy to pull off and makes them sit up.
Appasionata I put 2nd becuase by this point I'm used to the piano and should have an advantage on that awkward opening to get the right sound. People said "don't play appasionata it's overplayed blah blah..." But don't let that ever put you off. I had a statement to make with that piece so I made it. Overplayed pieces are only a problem if you play them like other people.
Liszt was just fun, and short, and showed that I had technique. They assume that you've played Chopin etudes, and will probably ask you about them. I got asked how many have you done? etc...
Don't worry about times, etc..unless you do somethign stupid like play Liszt b minor sonata lol. They say... at LEAST 15. so offer 20 mins to be safe. They will stop you.
Be prepared to play twice as well!! Since they have loads of applicants they usually send you through 2 rounds of auditions, or an interview.