Without a two year employment history and a current job you cannot qualify for a mortgage. 

Would I need to obtain any other documents?  

I should mention at this point that I had screened the tenants and they had excellent credit scores and rental history with no criminal record.

The only thing is that I lack a strong established history in credit.

Also, is filling it out the only documentation required to complete the purchase successfully?

It’s got a bit of a rough history and I’m looking for a local agent that specializes in, or is at least very familiar with, local laws regarding foreclosures to make sure I go in with my eyes wide open.

The RFTA packet is the formal documentation that you will need to complete in order to begin the enrollment process with the Housing Authority.

I could pay the loan off any time but like to show a good payment history on items.

they might affect your home especially if it is already adjacent to a denser zoned area.If the home has a verifiable history of use as a duplex it may be grandfathered legal.   

Regardless of what you are doing, you need to have a contract with an agreed upon scope of work document (pending on size of project) with every contractor that you work with so that this does not happen in the future.