There's also the idea of buying one for cash and then opening an equity line of credit for the future?  

Guessing you're desirous to turn your Pittsburg dirt into profits, I think you're on the right track though will suggest strongly that you yourself or someone very knowledgable that you can trust and manage babysits the process down to keys in hand, as I assure you, dealing with contractors and all entities along the developer's path takes an entirely whole new layer of skin and nerve.

I am in the process of getting financing from my credit union for $600k for 20yrs @ 4%.  

The better track record you develop with a lender the better their terms may become for you.

We cannot do conventional financing for at least another year and would honestly prefer to have a deal such as this being an owner-will-carry type situation where it is not on my credit (tying up my ability to purchase a house elsewhere).

In speaking to the PM company, I was told that the delinquency on the 12 month P & L tracked the monthly change in delinquency; if we started the month with a delinquency of $1000 on the first and at the end of the month it was $1500, only $500 would show up for that month's delinquency and the overall delinquency balance increases.

I realize it may be an ongoing battle to pursue low-income, but there are ways to track anyone down to levy or garnish -

Then track it to do follow ups.

I'm on track to receive a streamline FHA 203K rehab loan.

Matrix would not take it on, yet they have been willing to guide me with my questions and their advice and I learned so much from my first deal, that it just helped me lock up this one.And yes, it was not my money, credit, forms, or solely my personal knowledge.