Welcome to the forums! 

It's up to you.  Is it more important to you to have that money in savings, or to have your loan paid off?  Installment accounts are a very small portion of your overall credit score, so it's not going to make a drastic difference either way.  Personally, I would just keep making my small payments.

If you paid a big chunk, you would reduce the principal owed, not your interest rate.  It should not affect your interest rate at all.

I have yet to pay off any of my student loans, so I can't tell you what the most "hassle-free" way to pay one off would be