These people have just seen the ownership of the roof over their head change hands.

He's already put a tarp over the leaking roof -- exactly what I planned to do, except I would have done it in brown instead of totally obvious blue).  

Anything built before the 70s will most likely have issues with plumbing or electrical, and roofs last about 20 years, and should be permitted most the time on county websites. 

Subsequently, we discovered multiple leaks in the roof, resulting in water damage, including mold growth in our closet.

The house needs a roof and the existing roof is very old asphalt over cedar shake so according to the roofers they need to completely remove everything down to the rafters and install 5/8th inch plywood then reroof from there (one estimate so far came in at $31k for that).  

Fun fact to keep in mind, major capex items on a 100k house and on a 800k house are pretty similar, i.e. cost of replacing a roof.   

within the next 3 - 6 months duplex /triplex in or around my area although  the funds are week due to a high DTIalthough i have a 740 credit score, some larger purchases/ home improvements ,solar /roof /windows  have led me down the borrow pay later mentality..

We talked and I told her I'd be interested in it (1800 sq built in 1952; 1+ acre fields behind that are forever wild; mid-century feel to it newer vinyl siding/newer windows/new roof). 

Here are some other facets of a rehab which may be more expensive, roofing, windows, HVAC. electric service exterior and interior.

Something easy, like paint, floors, maybe a roof.