@Chris AdamsI doubt you can get someone to remove all the drywall and reinstall for 7,000.Also CDW was corrosive do most likely your electrical at a min would need to be redone

1) exhaust fans that stop working because of corrosion due to tenant showering with very hot water and filling the bathroom with steam all the time?

For example, in beach markets like the Emerald Coast of Florida, where I am, ACs need to be replaced more frequently due to salt air corrosion.  

These chemicals will cause corrosion to your cast iron lines and eventual leaks.Instead, try using a drain cleaner that uses lipase enzymes to break down the clog instead of chemicals.  

As I recall, there is also a corrosion inhibiting gel that prevents the wire surfaces from corroding which also increases resistance at the splice causing heat. 

Something I've heard about recently is that copper piping is highly susceptible to corrosion in FL, something to do with the soil/water content?

Galvanized steel plumbing is something to keep in mind because the corrosion on the inside of the pipes can really restrict your water pressure/flow over time.

It is also likely there have been numerous water leaks over the past 10 years or more that have further damaged the electrical system by causing unseen corrosion of conduits and boxes, potentially with water penetrating into the conduits and accumulating in low spots.If some/all of the above is accurate, your Board should have been well aware of the condition of the system, especially visible components such as the meter boxes.

I know they had a ton of issues in those houses, I've even seen some pictures of the wiring,outlets and plumbing in the walls having corrosion issues because of the humidity and mold issues.

Worst case with metal is that it gets dented from hail and gets surface rust and corrosion and needs to be sanded and painted again in 30 years.