ReedThese books will give you a solid understanding of sound investment principles which you can use to build your multi-family portfolio. 

I have found some great resources (https://www.biggerpockets.com/blog/2015/12/03/structuring-partnership-rental-properties/) but none of them discuss returning principle to the lender.Example:Managing partner A (me) and funding partner B (them) decide to go in on a multifamily. $200,000 property 20% down + $10,000 rehabFunding partner funds all $50,000.

Just finished RE principles and should have my license by the end of December.

My goal is to own all properties free and clear within 10 to 15 years; and I set my extra principle payments accordingly.

We did get turned down by a local bank since all of the principles are out of state.

I figure after 7 years I will have made 2.5x my initial leveraged investment from both positive cash flow and principle paydown.

Does the seller need enough cash to put a new roof on his principle residence?

If it hasn't appreciated, you haven't made much money, other than your principle payments.

@Joseph ShawI'm a big believer in the DRY principle (don't repeat yourself), and so I use quickbooks and only quickbooks for all of my cost accounting and cost tracking and reporting. 

My returns on my rentals are so much higher than any of the interest rates on my cars or principle house.