As mentioned above, in the "subject to" method, you purchase the property "subject to the mortgage." 

I understand the 70% rule and I know of (have yet to practice) the fixed cost method for calculating MOA.

I have done well over 150 ceilings with that method and it makes it much nicer than wetting and scraping.

Integrate your methods.

To fix it right, you'll want to keep going until you don't find mold anymore.I disagree with Christian's method for fixing it, but that's mainly because I'd be comfortable "doing it right" without a plumber.

Having been in the field of Marketing for over 20 years now, I've always advocated integration of marketing methods.

Accounting methods can smooth some of this out, pro formas are best guess especially for student clientel.

The cost will likely not be much more than other less effective methods and the energy savings would likely be higher, plus the resale value would be better.

However, to appease the buyer, if the home is old enough to not have a ground wire in the cable sheath, then the cheapest route is to install GFCI outlets or breakers for the plug circuits, as compared to running ground wires to all the plugs, & this method is code compliant.

The typical methods I've seen (and used myself) on both interior and exterior block walls is to anchor vertical strips along the wall with Tapcon screws or masonry nails.