Private Lender Cash ROI calculation/Newbie Questions

[Shayne Skeans]

So I'm new to the real estate business and looking to buy my first rental property with cash via a private money lender who is a longtime friend of mine. He's agreed to front the cash to purchase a property and rehab it if necessary at an interest rate of somewhere from 8-12% return on his money. I'd be doing all the rehab work myself as well. So one of my questions is would I be able to immediately be able to start the refinancing process on the property and get a conventional mortgage on it after closing or do I have to wait the 6 months? Then how would I calculate ROI for that property? Since I didn't technically put any of my own money into it at this point. Sorry if this seems like a dumb question! Really new to this stuff and trying to iron out any problems that may arise instead of being blindsided by them.

Another thing I'm not sure about is actually being able to refinance the property enough to recoup all his money and get it back to him.  This is the primary thing that makes me hesitant to take him up on his offer.  Is there a easy way any of you have found about estimating what kind of mortgage you can get on a property you pay cash for other than a pre-purchase appraisal?