Yeah, I attempted to contact owners a few times without success several years ago (without doing a large campaign - young, dumb, and very green).

@Dan Green is up to the buyer or his lender to get an appraisal, do your best to estimate rehab and market value and price property accordingly.

Are there any parts that I should really try to do myself, if I have time (I'm pretty green at DIY)?  

@Sam Leon Water dispersion is one of the characteristics of a Green Roof ;-)  It is quite possible the compost on your roof, and the matter growing in it, was masking the leaks.Termites are something with which we thankfully do not have to deal up here ... yet {I hear they are in parts of Maine now, so it will just be a matter of time and a couple of mild winters before they find the tasty old Second Empire, Queen Anne, Victorian .... buffet which awaits.

I am still very green if you can't tell already so I'm looking for any kind of advice.

@Brian Gibbons  Thanks Brian that link goes to Green Leaf, a servicer who took over a CitiBank note of one of my rentals.  

Every single water line on the toilets, sinks, drains, you name it either had silicone in it or some mystery green sealer.  

It looks like the lots that are on the same block to the south a little have been changed into multiplex buildings with little green space left, one has a garage (4 stall) the others have large concrete parking slabs.  

In fact color me green with envy on some of those deals you have posted. 

its so green and the people are so nice.. and we have a Nike outlet store !!!