12 property owner financing deal

[Johnny Quilenderino]

I have the opportunity to buy 12 SFR in a C and D class area. The gentleman is getting out of the business and is offering owner financing. All of them would get 300 dollars a month back after PITI. I would need 18k for broker and realtor fees, plus another 5k for the termite and home inspections. What questions should I ask? What contingencies should I put in the contract? How should I go about paying off each one individually once I have them? I already have a HELOC pulled for the 23 k needed for the transaction. Just worried that I might be over-extending with all twelve at once. Any feedback would be greatly appreciated.