$316,500 total acquisition cost, $55K~ approx. rehab cost.A lot of the major costs (plumbing, electrical, roofing) were needed to pass inspection upon re-sale so I had no choice. 

I hate to leave money on the table, but I believe I made the right choice by taking the bird in the hand and not risking 180 days on the market.

Billing directly as the others have stated would be the logical choice as long as your lease agreement supports it.

But, why are the canceled checks and deposit statements on my end not sufficient? 

So, we set up a time and tell them they can be there or not, their choice.

(For Sale By Owner is not considered sufficient in attempting to market a home).  

I am still learning to run the numbers so I need to speed that up so I can be more knowledgeable in the choice I make.

When you choose to do something, do it knowing that even if you love 80% of it, there are always aspects that you will not love dealing with and potential risks associated with your choice.  

(assuming I would most likely have to buy a note outside of my state (Florida)Is 40k sufficient amount to start investing on NPN and research all variables to make it a good deal?

Their choice.