The foam insulation insures that any possible dust from the nail penetrations is contained and therefore does not endanger the applicators or anyone else.  

I seriously doubt the credibility of a serious investor who would sell his knowledge, to create competition, and endanger his livelihood.

The neighbor's letter says that a tree on my property is endangering their home, and needs to be removed.So it looks like the selling agent (or agency) was aware of this when they facilitated the sale, and they never disclosed it.

@John Kim to do a smart deal and not endanger yourself is key in REICash or terms, low cash or great terms.  

And before anyone decries "cabal, CABAL, they did it to us" let me ask you, if a person opens a restaurant serving double bacon cheese burgers and other cholesterol rich foods, is it a cabal to serve health endangering foods, are they with secret mission to kill people, or are they simply serving something people really like, line-up to buy, giving the people what the people want as evidenced by the people "voting" with their consumer actions?

Residential code enforcement officials love good, honest renovators who don't endanger the community.

If the market crashes, and you have paid off properties well, rents may go down but you would not be endanger of losing them. 

Would I have grounds to open a law suit against them for destruction of property, endangering tenants, and causing a lawsuit liability for us if they don't fix the situation?

I am an investor originally from Northwest Ohio but have spent the last 10 years travelling the Mountain West working as a Park Ranger and Endangered Fish Field Technician.

Boeing focused too much on immediate ROI, and made decisions that have endangered the company with top management relocating to Chicago, and losing touch with the factory floor from what I read.