As far as your next property, if you are already considering moving you will get better loan options + interest rates if you decide to live in the next property and rent out your current house. 

Your first step is- Get approved for a loan (unless you plan on paying cash). 

Once the rehab was done I refinanced out of the private loan into a conventional loan as a primary residence.

Do the math at a 6% loan rate.There's a reason many apartment buildings have been converted to condos and sold.

Rates are high, usually in the high 8s or low 9s, and you may pay 2-4 points on the loan. 

THe lender is a credit union and it is a conventional low rate loan.

His "buyers" - who could not qualify for a loan because, presumably, they could not convince the bank they made enough to cover PITI payments - inevitably defaulted, and after a few months he would evict and start all over. 

If the other two parties want to flip a house maybe they can do just that as partners and then sell you the house which you can buy with a primary home loan with low down payment.

You have a bigger loan, but not a bigger tax basis.

A non-recourse loan is an option if your SDIRA doesn't have enough funds.