Welcome to the community, @lremee87! This is a no-embarrassment zone: Doesn’t matter if you’re clueless. What’s great is that you’re looking to learn!
Let me try to tackle your questions one-by-one:
Interest is the “extra” cost you’re charged for borrowing a loan. For student loans, interest “accrues,” or is earned, daily. Because your payments are so low, more interest will accrue on your loans.
You don’t have to avoid accrued interest using REPAYE; one of this plan’s best features is the government pays it for you if your payments don’t cover this amount (which $0 payments won’t). This benefit lasts three years for subsidized loans. Half the uncovered interest will be paid on your unsubsidized loans for the same time period. After those three years, the government pays half the interest on both types of loans.
You could pay off the interest on your unsubsidized loans that isn’t covered, but I doubt those small amounts would have a big impact on your credit score. (Though I’m hoping one of our credit Nerds will chime in on this.) I’d suggest putting extra money toward your principal balance instead.
Making extra payments is a great way to pay off loans faster, though your servicer may not support weekly automatic payments, if you wanted to go that route. Try out the calculator on this page to see how much you could save:
I hope this information is helpful. Definitely post back if I missed anything or you have more questions!