Was the option to pay bills on a University Housing lot (penthouse or otherwise)? And did the Sim have student loans taken out?
As for the roommates, were they NPC roomies or household roommates?
If you live off-campus you'll have bills. I'm guessing that if you take out a loan, you'll have the "bills" option where you can start paying off before you graduate.
The NPC's household funds shouldn't be added to your Sim's funds but if you move into dorms where Sims already live (which a lot of the Sims Camp videos had), they'll be added to your household & their funds merged because they're not the same as NPC roommates.