Benny- day of bench exam you can wear whatever you want. I would suggest dressing in layers so that if you are hot/cold you can take the layers off/on accordingly.
Alident- they will NOT tell you to do a 7/8 crown. they will give you a case scenario and ask you to use your best judgement. For wax pattern they give you a block of wax and dimentions for a tooth (last time it was #8) and ask you to carve it out of the wax block. for RPD Design they want you to take a red/blue pencil and make a design on PAPER (Not not not A MODEL). kind of like a design you would give to your lab technician if you made an rpd for a patient. last time it was Class II modification I i believe .
as for cavity prep, again, they give you a scenario so you ahve to use your best judgement!
heres a hint- like trintrin said....DONT BOTHER buying ALL the instruments they ahve listed, it will cost you literally $3000 ....just use what you have and take your OWN TYPODONT and instruments. USC will NOT give you anything.
Hope all this helps!