He planned on doing this last project in 2019 but his health has deteriorated and is now looking to sell the land with all the architectural plans etc.

you should actually get your deposit back based on depreciated age of the countertop especially if it was already in a deteriorated condition.

Plumbers charge an hourly rate, materials (marked up prices), and sometimes for additional costs like equipment rental or mileage.Empty houses deteriorate.

Lead paint itself is not dangerous - it's the lead paint that is deteriorating—peeling, chipping, chalking, cracking, etc, that is problematic and requiring remedy. 

I'm acquiring a property in Galveston, TX and would like to keep the a more regular eye on things that may deteriorate faster than others due to salty air/water exposure.

If the foundation is deteriorating and needs to be addressed now; then you need to get some experts in foundation to give it to you straight.  

Neighborhood deterioration leading to long term rental rates falling, as well as occupancy and quality of tenant.

When it was pointed out to the seller during the walkthrough yesterday, he answered that he will "tap it back in", as if he has done it before.In the seller's disclosure, he marked "No" on any history of walls/foundation shifting, movement, deterioration, past or present. 

If the foam is deteriorated you could cut away the expanding foam as best you can and get another can of it and refill the gap, then when it's dry cut away excess.

@Taylor SmithBe on the lookout for powder post beetles, knob and tube wiring, lead based paint, and deteriorating fieldstone foundations.