I own the main parcels (80% of the land with the utilities--appraised at $450k); he owns the other 20% ($116k), which is a split off a multifamily property he has.

Our next step is to find out if vacant or not (our realtor seems to think is occupied), offer a small $ incentive to said tenants to move out in a nice and tidy fashion as to avoid damage to the property (if not, start the eviction process), get utilities changed in our name, get title insurance (via taxtitleservices) /clear the title, then work on the rehab :). 

This story is so common that everyone can just copy and paste what you just posted. 

Regardless, the Board adopted regulations that all but eliminated our options to rent the place, including a proposed $250 fee per rental for "administrative costs" and requirements that renters sign an extensive agreement about what they could and could not do on the condo common grounds. 

The job did not produce any document/receipts for obvious reasons, and common sense would tell me this is not possible.

I think they are more common for "for sell by owner"

I refinanced with a local bank from a 20/5 4.9% to a 25/7, 5.25%, it not common but it's out there, just takes some looking.   

That is common knowledge and the sentiment of sellers reflects it.

Make sure on your rental agreement that people understand they are renting a room with shared access and responsibility for the common areas.

The Radio Utility Billing System seems really affordable and logical but I can't find a company to do this for such a small unit size.