For calculating IRR, use the total cost of acquisition—this would be the mortgage balance plus the 50% buyout equity and any closing costs.Regarding refinancing, assuming the loan under the Garn-St.

The loan is with you, not with your tenant, so none of that means anything to them - in fact because you live in one unit and it's under 4, if you were self-managing you don't even have to abide by fair housing laws (at least on the federal level). 

I would take out a private loan on the paid off property to get the other one squared away

These typically account for about 80 to 85% of all expenses in a flip.If you know the lenders' terms and the loan duration, lender fees, the second greatest expense, are easy to calculate.

I was looking at DSCR loans because they don't require extensive checks like the bank loans and they "only" look at the income generated from the property to qualify for the loan.

They would also provide the funding and renovation funds at 7%.  

Has anyone have any experience acquiring multifamily property using a SBA loan like to get your thoughts?

I have multiple lenders that can do 100% financing for the short-term rehab loan, up to 70% ARV for 1-4 unit properties.

I was thinking a bridge loan might be an option , and then refi it later and pay back the bridge loan,  but I'm waiting for lenders to reach back out and run some numbers.

I only wanted to clarify that almost everyone who mentions their equity means “cash after paying off their loan”, not their gain.