here's my take on the matter (from someone who has done a few auditions for stuff like this):
you want to look your best, and to look professional and put-together for the interview/monologues/songs portion. so i would suggest dressy casual, like what you would wear to a job interview. don't wear your jazz shoes into this part, save your dance apparel for the dance part!!!
for the dance part, wear appropriate dance attire. i usually wear a black leotard and black jazz pants...but that's just me. whatever you feel comfortable dancing in is fine for this - but nothing too loose fitting. they'll want to see your body and that will be hidden if your clothes aren't fitted enough.
good luck! i hope you get in!!!
maggie
"grace, you're stuffed in a box getting rid of ass plaque. let's face it, this evening is a bust."