Hold your head up, be professional in this transation, and never work with him again. 

But the ones making money in your market may be professional real estate investors rather than a novice investor.

I'm interested in connecting on both casually and professionally, so would love to hear from seasoned investors and the greenest of the green.

These are professionals with additional training and a stricter code of ethics.

A four unit can never generate enough revenue to get a professional management company (neither can my 20 unit honestly), so you are stuck with what you are seeing. 

I've discovered that:They only work with industrial and/or retail (and seem curious/surprised why I'm investigating apartments)They are the listing agents for properties in the area (it is a sellers market where I live).Being a first time investor, I'd like to have a trusted professional in my corner; using a listing agent (at least to me) represents a conflict of interest.Should I be cold calling firms outside of my immediate locale, such as major cities nearby (or national)? 

My experience is in professional property management, at A+/luxury caliber apartment buildings where expectations are high.

You can even do some of this yourself, but you probably will miss a lot of things if you don't have a professional assisting you.Best of luck!

The seller produces a document showing there is no leak (i think by a professional).

Make sure you talk to your tax professional.