If you work as a cashier at a fast food place, you will not be close enough to grease for it to affect your acne. That being said, acne flare ups aren't exactly the best reason not to work in fast food. Acne sucks (believe me, I know), but it's not a good enough reason to avoid that job. Now if you were deathly allergic to grease...that would make more sense.

As for the spending habits, that is something you need to work on then, preferably with a therapist. I can also relate to having bad spending habits...but frankly, it seems like you're giving various excuses as to why you can't succeed. Why are you holding yourself back?