1. You just confirmed what I said. If one girl or two, three... doesn't matter - are prostituting themselves, that would be a low profile. Somebody could rat on one of them and she would be in trouble. Rest od them would continue as before.
BUT - we're talking about ORGANIZED prostitution ring - with one person selling girls to clients. That, my friend, is much, much bigger crime. It also brings much more money and is riskier. Just one of the unsatisfied customers and you'll have a campus full of cops. Because of that, such thing can't run for years without someone powerful enough to keep it safe.
2. Drug trafficking is in the game. Or do you think DIKs won a lottery and they bought a mansion? And Tommy's offer is promise to Quinn they'll help with study and tests?! And Quinn is testing Tommy's gift - probably insulin, right?
3. About Burke - no, we don't know absolutely anything about him. We don't even know he's teaching economy. He could be anything or nothing. But, as a professor - or maybe even dean (we don't know, really), he has much more power and influence than just one student - in this case, Quinn.