If you wanted my opinion, (and I hope it is still valid!), I would play a lesser known Prelude and Fugue. For an audition I did, I played BWV 875. It's not too difficult if you like scales, and you can really bring out contrapuntal ideas in BOTH the Prelude and Fugue. A sinfonia may be a little short in duration and, if not played convincingly will probably bore the panel.
The Mozart Sonata you gave seems like a good idea in fact I could only throw suggestions at you which would probably be equally as good as what you've chosen.
The Chopin etude seems like a good idea, though PLEASE play it well. It's a pretty well known one out of the 24+ etudes Chopin wrote so it wouldn't be surprising that someone else has played this too. Something like Op.25 N.7 could go well if you find learning, (unless you have already), Ocean to be a little taxing, and again gives you the opportunity to be varied with a slower piece but still show off virtuosity with control. You could even be a little sneaky and put L'isle Joyeuse in here if you wanted to, (it would save you time!), but may be a little risky when it comes to the 'Is he too impressionist for Romanticism?' debate. Of course learn the Chopin and if you find yourself clutching at straws you have some kind of back up!
In terms of a 20-21st century piece - this may be a bit bold but I'll say it anyway: Kapustin?! I mean he is living, and highlights the requirements perfectly. 'representative of musical elements over 100 years' - Jazz, sometimes a little atonal also (20th century there). And I guess him bringing the classical forms of Preludes and Etudes etc like Shostakovitch, (but in a less threatening way!

), would again justify you. You don't necessarily have to play 'classical' sounding pieces in terms of what's required, so why not? It'd really set you apart I think!
Of course these are all suggestions to take into consideration. If you are really sorted with a programme then I wish you the best of luck with it!
