Do you mean paying as in private tutoring? Not from experience, but lots of people do that throughout high school and even college. Hence why you see lots of preppy rich types at the exclusive private universities, because money = more learning advantages, unfortunately.
I would pay someone to magically raise my current GPA though
I have a terrible guilty conscience, I don't think I would live through my uni life knowing the reason I'm doing "well" is because I'm buying my way into it. I like to think that people deserve the mark they get (obviously there are exceptions), so yep, I definitely deserve to fail if I suck. It does suck though because I've been through a lot of bullshit in my life (will spare you the details), so it's hard to study at my optimum level, which is why I'm currently taking a break from uni to really work on myself.
Nope.
I've gotten far enough into my classes where they care very little about your GPA unless you're falling below the minimum.
There's a point in med related majors where it's no longer about your grade, but what you can learn to help your future patient. If you misdiagnose someone, it doesn't matter if you got an A in that class in college.