The closing attorney would wire funds to the lender for the release amount and they would clear the deed for that specific property. 

Cash on Cash is the % of the return ( your profit after expenses) against the amount of personal money you have invested in the property. the less money you have into the property and the greater the profit the higher the cash on cash % will be.

Zillow, Rentometer, etc) that have info on properties that are/were advertised for rent and what amount they were advertised for. 

Now, before you say that I should have gotten the closing cost wrapped up into the loan amount... we couldn't do that.

Will there be a promissory note detailing loan amount and interest paid.

Please click on the links, give them a read, and share your thoughts in the comments.First is a post that I feel will help not get overwhelmed with the amount of info that is here on BP:https://www.biggerpockets.com/blogs/5868/52761-the-simple-guide-to-getting-started-on-bp The second is a post that will help get you focused with your real estate investing goals:https://www.biggerpockets.com/blogs/5868/52743-im-new-to-bp-any-advice-would-be-appriciatedThe last one is a post that will help you choose an “investor friendly” real estate agent.

The tenant doesn't own anything until the option is exercised and they actually buy the property.Owner financing is the owner acting as the bank with a promissory note with the terms of payment (principal amount, interest rate, number of months).

Please click on the links, give them a read, and share your thoughts in the comments.First is a post that I feel will help not get overwhelmed with the amount of info that is here on BP:https://www.biggerpockets.com/blogs/5868/52761-the-simple-guide-to-getting-started-on-bp The second is a post that will help get you focused with your real estate investing goals:https://www.biggerpockets.com/blogs/5868/52743-im-new-to-bp-any-advice-would-be-appriciatedThe last one is a post that will help you choose an “investor friendly” real estate agent.

Is there an HOA amount? 

You may not be able to touch his deposit unless he damages something or stops paying but if he agrees for you to keep a certain dollar amount, he won't have a leg to stand on.