I think that's perfect. I think the school would ask for a piece w/ extended techniques if that's what they wanted to hear. I think for nearly all grad schools, that repertoire is absolutely perfect. The only places I would imagine would expect extended techniques would be Curtis, Juilliard, maybe USC, Yale, or Colburn, or if you're auditioning for Robert Dick. You could drop a line to the professor just to verify, but I think that's a great selection. They love to hear Mozart, but no you don't have to play it. I think it would be refreshing to hear such a great work as the Mercadante as it is not played as often as Mozart in audition settings.
oh, i just checked, and Hartt asks for some extended techniques. But, as I said, I think any school who wants to hear the extended techniques will ASK for it, as they did.
p.s.s. i think you should have a few orchestral excerpts ready and maybe 1 or 2 piccolo excerpts. those are pretty standard for any audition these days