Newbie here...does anyone use it, whats your thoughts?

I was going to bring up that the seller financing doesn’t matter if you plan to get a construction loan as the seller financing will have to be paid off. 

I just include the utilities in the rent.

And you have taken the extra 150 hours required for the broker's license? 

Please keep in mind investors, not every deal that you place under contract will close - that's just the nature of the beast when it comes to investing. 

Then I put about $45,000 in fixing it up and I expect the appraisal to come back within the next couple of days at $240,000 or higher. 

Specific topics come in waves.

So there might not be enough gain to need a 1031 exchange.If there is enough gain to justify the 1031 exchange then simply treat your replacement property as you would any other investment like @Daniel Osman said. 

What documents do they require, what credit scores do they allow, how do they verify previous rental history, etc.?

Call up a couple companies.