I would be sure you understand their draw process: costs, requirements, timelines on draws.  

That will change over time because it's becoming such a huge draw for everyone.

During a duplex renovation, do I need to get an individual invoice for every draw from my contractor for tax proof purposes or as long as I have proof I sent the money and a signed contract with due dates, does that suffice?

I understand that I'll need to submit a detailed plan and drawings to the city in order to get either approved.

Can you help me draw a line in the sand between the 2 statements and how they both could be achieved?

And like everyone else has mentioned, definitely speak to your RE attorney and have them draw up the right paper work. 

@Jake Greener find a mature-drive to-vacation market with favorable regulations and an outdoor draw (lake, ocean, dessert, mountains) and buy a property.

Seeking some advise about to close a deal on a duplex and a single family home both owner carry...Any recommendations on the best way to draw or write the contract?

Needless to say, through FHA this was a pain with all of the guidelines, inspections draws, and of course there was a huge learning curve since this was my first deal.Move to today and I am currently in contract on a 2 unit with an unfinished basement and am using an FHA loan to close on it.

Ask yourself why you are interested in real estste, what is drawing you into this field?