A collection agency, PI, or a company looking to perform due diligence on its customers would have permissible purpose.  

Lots to the story, but it boils down to poor work being performed initially and a project manager that let things slide.

The market and rent appreciation really made the properties sing and perform phenomenally.  

I'm trying to learn whether an exit on a property should be dictated by a time frame (5-7 years), a property's performance, or a combination of the two.  

Do any of the services above need me to be a real estate broker to perform on behalf of another landlord if I charge them a fee to do this?

And if the OP doesn't want to perform what most, frankly, would consider a small act towards developing a relationship... why would the bank want (using the OP's language) to go out on a second date?

If the option is never exercised, then it is basically just a rental.Contract for deed you agree to pay the price of the home in monthly payments over a certain period of time.

My health took a turn for the worse, and my performance on the job suffered greatly because of the treatment.  

As I see it, your options are a warning letter/discussion, a 3-day to perform or quit (regarding quiet enjoyment of premises), a 3-day to pay when the rent is due (but I stress again constantly collecting on the 10th has tacitly made the due date the 10th unless you reset with a change of terms), or flat out termination with a notice to quit (30 days if living there for under 2 years, 60 day for 2+ years, or 90 day for a HUD tenant or as your housing authority requires).

Chances of his bill equaling exactly what is due from him are virtually guaranteed regardless of work performed.