If I use Sallie Mae and then my financial aid kicks in while using it will the fa money automatically pay it?

I'm not sure what you're asking exactly. Are you asking about getting loans now and grants that may come through later? If so, then your tuition will already be paid by your loans, so if any additional money came in your name later, the university would refund it to you. At that point you could choose to pay off the loans you took out or spend it however you wanted to.