Seller Financing: Balloon, Refi, and 1031s!

[Charlie Cameron]

Hi all!  My wife and I are have started actively seeking deals and are getting really excited!  We think this is a way to supplement our military income once we retire in 16 years!  

While we have traditional financing lined up, we'd really like to use seller financing on as many deals as possible to keep more cash for more deals.  But we are new to this, so here are three questions we really need help with:

1. Can you arrange 30 year seller financing without a balloon?  As in, the principle wouldn't need to be paid off at 5 or 7 years; you could pay the mortgage as long as you want or pay off the remaining principle whenever you wanted.  Is that a thing?  Is there a disadvantage?
2. Can you refinance seller financing with a traditional lender whenever you want?  As in, can you pay off the seller's note as you start a new one with the bank?
3. Can you use a 1031 exchange on a property you still are paying the seller for?  

Any insight is helpful!

Thank you!

Charlie and Greta