I would imagine the best actions would be to immediately fire the management company, pass the keys onto a new one, sue the old one in small claims court for the listed damages.

What steps would you recommend to minimize damages and resolve this issue efficiently?

Especially if seller just received a windfall from the sale it is definitely worth suing for damages.

However, if for example, the company did not install or disconnect the washer and dryer correctly (such as leaving a valve on) while water is turned off prematurely, causing damage, what language do you put in the Lease to also hold other parties accountable such as ALE and appliance install company?   

Sounds like an unreasonable seller and the most likely reason for them not wanting an offer with a financing contingency is the property is in too rough shape to get financing on it (structural damage, fire damage, etc.) or won’t appraise anywhere near asking price.   

Tenant further acknowledges and agrees that they shall be liable for all damages to _______ system due to intentional or negligent acts by the tenant, it's invitees, guest,  agents or licensees" 

It will be interesting to see how all this plays out during an investigation, but I sure hope that the money can be followed for the investors' sake that were damaged here.I've also been made aware that a company, Tardus Wealth Strategies, who "coaches investors on financial independence in 10 years or less" was heavily promoting the Norada fund to unaccredited investors and was also heavily promoting Ron Fossum. 

During your initial walkthrough, inspect the property for any major issues such as structural damage, roofing problems, plumbing, and electrical concerns, while documenting all cosmetic and functional issues with detailed photos and notes.Once you confirm the property’s potential, finalize your ARV and calculate the repair costs using either a reliable estimator or insights from contractors.

You can look at a mobile home and see it as an easy rental with new carpet, trim and some paint but there are other bigger uglier expenses that can come up.Roof Replacement, soft floors (water damage) in kitchens and bathrooms- most floors are particle board, exterior door replacement (special order), underbelly insulation falling, bad hot water tanks with rotten floor underneath (real joy), bad windows (water again), bad bloated siding (water), water damaged base frame around perimeter of home, cracked tubs (special orders) and frozen pipes (Good luck finding a plumber to come work on a mobile home- they do not exist). 

Not worth the liability risk and the potential damage pools leave.