I don't see how they could send a collection agency to you or anything if you didn't sign anything with them. 

Rather than reinvent the wheel, I wanted to tap the collective knowledge of some structures to have an investment model for buy/hold without locking my own money up.The pain point is the exit.

Usually my finds are for houses needing light to extensive rehab, although I have bought move-in-ready.  

Every month he sends the payment after collecting their shares of the bill.

That's great advice because you need to be cognizant of Fair Debt Collection laws. 

After an extensive remodel I realized I could rent the unit I was in for more than I would pay to rent a unit for myself in another part of town and moved out.  

It will depend on the insurance policy of course, but I know several apartment complexes minutes from me in the Germantown neighborhood and they received extensive damage and had to release all of their tenants from their leases because of reconstruction of their 100+ unit complex.  

IMO, if you aren't doing extensive rehabs on Detroit homes it's not worth investing there.

In the last few years I’ve done a fair bit of research and reading on Real Estate and have been studying the subject extensively, almost to the point of obsession.

I did fully close this property myself and collected rent for 2 months before selling the house.