Our instincts are to eventually rent it and use the income for payment assistance on a new home mortgage.

I'm speaking of co-living in a typical A or B level neighborhood house, so instead of a 20-25% down payment, we are speaking of a 1-5% down payment. 

If you tried to use the app to look at photos of your ads or look at the "charges" for rent payments and such it was pretty much unreadable and would have several glitches making things overlay on top of each other and such. 

You could front the down payment as well as monthly payments to the seller, then charge interest on them.

In addition this fire storm started when payments stopped or payments were returned to the bank NSF.

Each property has two savings accounts - security deposit & reserves, and one checking - mortgage payments and utilities 

The main issue I have is contemplating the baloon payment at the end of the 2nd year and refinancing the remainder with a bank...how can I compute that into calculating the IRR?

the rest of the loan payment right now is coming back to you eventually. 

By the time I reach 20% equity (likely 3+ years away), my monthly mortgage payment will come down when I refinance, but $600 is a big hit to the numbers. 

1099, social security, trust payments, annuities, etc?