How do you know if the appropriate upgrades and remediation have been accomplished.  

I was pretty much the same situation as you are in, except i did not think quick enough about the additional pre-close negotiations mentioned above.In my case time after closing i dove in to set expectations and address/remediate all concerns from the previous landlord, and since then i haven't had any troubles.Thank you for the post!

The costs to hire a structural engineer and then remediate the problem was far greater than I was willing to spend for a buy and hold.

And to call me immediately to remedy the problem. 

Mold remediation can easily run $15,000 to $30,000 and since it’s a condo you don’t know where the source of the excess moisture is coming from.

if the numbers work it shouldn't be a deal breaker, get a mold abatement company In for quotes to remediate, plan on waterproofing the exterior basement walls and adding heat to the basement if you plan on doing anything with it

You may only charge the tenant if you actually incurred costs to remedy the damage, and, this cost must be presented to tenant in terms of repair bill and receipts for payment of the bills.  

In those cases or other specified large rent increases that cause displacement, landlords would have to pay relocation benefits, with increased benefits for the disabled, seniors and those living with minors.The measure would also create a nine-member rent stabilization board to determine annual adjustments, hear petitions for individual rent increases and pursue remedies in court.

Real estate activity; unlicensed personA.(1) In addition to any other civil remedy or civil penalty provided for in this Chapter, the commission may issue a subpoena to any person or persons who the commission has probable cause to believe has engaged in real estate activity without a currently valid license.(2) Subpoenas issued by the commission shall comply with the notice requirements of R.S. 49:955.

However, given the potential additional complexity of a home having flooded, does this % hold true or what additional considerations should be made in purchasing a home in a post flood situation (house ONLY flooded during Harvey and not in any previous flood, mold remediation already taken place)