These answers will uncover if a lease option or a seller finance will be good for him. 

However I can't know the full extent until the walls are uncovered.

I have had to walk away from properties for the issues that I did not know, but were uncovered in the due diligence phase.

Two parking spots, one covered in front of condo and one uncovered not in front. 

One may be tempted to say you don't need to be an expert, which may be true, however, it may take an expert to uncover (before you buy) that 123 main st. is encumbered even after the sheriff sale - then you are in trouble....

You must have your accountant review his 5 years of P&Ls and tax returns to uncover the truth.If the property had equity, why hasn't a buyer stepped up by now to purchase it and cash him out of his equity.

Yes, a simple call or visit to the Building Department will uncover all permits ever pulled for the property.

This can be accomplished from the interior as well, however it's more effective preventing moisture from coming in (exterior), rather than holding moisture back (interior).been trying hard to avoid excavating. and remember now......there is a span of wall that is nice and clear...and not too cracked up. so whether or not they waterproofed or not........that span of concrete blocks are relatively undamaged. it doesnt make sense that they would waterproof that span, and not the other span.so this is why i think i can just cover the damaged span of concrete blocks with a porch or something so that water wouldnt get to the span of exterior wall. id actually probably use plastic tarp in the beginning, so i could uncover that area during days of sun in hopes that any moisture inside the dirt would evaporate. when it rains, id cover up that area again with a huge plastic tarp.i would also improve the grading, and well the downspouts are already good.i could also do a french drain type thing...but i dont think that would be necessary.im really trying to avoid excavating. i dont want to pay $25K lool. i already have mold issues on interior joists that will need to be blasted off...and these joists are 30ft long and there are probably 50 of them going across the basement. and yesterday i was looking at some studs...and i think i mightve seen some mold on those too. super annoying, man.

Need to do title searches to uncover any liens and check out the property for viability. 

If you know the cities or towns near you you are likely to find better deals and hidden gems that other may not have uncovered.