Purely my opinion ...The housing shortage is nowhere near resolution.

Odds are, you can gain an economic interest in the subject property but it will provide little resolution and limited control.

I found the county criteria which reads as:"Property must be minimum of 1 acre, meet the underlying zone district, have adequate parking, meet the requirements set for by the Wildfire Hazard Overlay District, have valid water and sanitation, have legal access, use the primary dwelling unit, be free of violations, and have no substantial detriment to the intent of the Zoning Resolution."

I would ask for a repair or credit on the resolution of unacceptable conditions and if he offers nothing, walk. 

If so, you can test each unit separately, as it seems obvious that the first floor leak would be from the second floor, but water is a tricky situation.For the roof, I would certainly get several groups out to let them diagnose the issue and bid the resolution.  

That may be the most practical resolution but if they stopped paying interest they may be struggling with liquidity. 

I am a very excited, resolute newbie in Mansfield Massachusetts and determined to get started sooner rather than later.

Welcome Sean, I am quite interested in the responses you might get as I have been looking around myself, best of luck although you already have a great deal done with your resolution I'm sure :) 

Maybe I should have waited a few hours and made my new year's resolution easier to achieve.

I dealt with this garbage when I repositioned my properties and I can tell you that you will be on parking cop/tenant dispute resolution duty going forward.The only way to deal with irrational children who are throwing a tantrum is to reward them with a picnic table and $50 grill.