For example, you might see a tiny bit of mold on a wall, but when you remove the mold you may find that the moisture has traveled in the wall to all kinds of places that you can't see.

My inspector also had a mold license and informed us those mold tests can actually be very simple and somewhat flawed as they come in with a handheld machine that senses moisture or whatever.

I have used it before, mike, and in a perfect world a cheap roll on product would do the trick, but all my moisture puzzles in the real world are so much more complicated. could be so many things, like where is it coming from... mere warm moist air condensing on cold places, a leak, slope or gutter problem outside, or an more costly drainage issue that means excavation around the house (for example., have you seen Holmes on Homes when they tackle tricky basement moisture the "right way" ).... so I would study it more (alot) and even think about experienced or expert opinions to find a source and craft the best solution.... wish I could say it is a 30 dollar and done deal....

Make sure you eliminate ALL moisture and wood to ground contact issues to help suppress future issues as part of the pest management plan to resolve your issue.

And unfortunately it caused moisture in the return, which led to the heat pump to start rusting. 

Due to the Flood,,disaster you may be able to give tenants immediate notice to vacate.. the option of letting them stay thru clean up is a health hazard and you don't want to expose yourself to unwarranted lawsuits from tenants because of work delays, mold, whatever..You'll have to refund security deposits, and any rent prorated from storm date..Similar issues in Texas with Hurricane Harvey,, landlords are having to displace tenants because of undue delays for clean up and repairs,, contractors are not available, and resources such as flooring, ect are hard to get and you have to completely let the place dry out or hidden moisture will be huge mold issue.

Shiva,A couple things to consider; Installation costs & maintenance for upkeep and repair Noise ( certain types of flooring are extremely loud)Real hardwood -one of the more expensive options -installation is time consuming as it has to be nailed down and then sanded/finished -biggest benefit in my opinion is that if your floors get trashed at some point you can always sand them down and re finish them Vinyl Flooring -cheaper than real hardwood -easier to install ( you can either glue it down or float it) - takes abuse fairly well especially moisture -while you can’t refinish vinyl if you float the flooring it’s very easy to pull it up and replace

Logic tells me to fix them both since the leak will eventually exacerbate the problem...not a matter of if, but when.If I fix only the plumbing, the slab may react and worsen possibly since I am removing the source of the moisture that caused the issue. 

I see so much flowers, seed pods and leaves, they sit on the roof and with the daily rain in South Florida the debris completely carpet that section of the roof in a matter of days, and with the captured moisture it causes the shingle nails to rust a lot quicker over time. 

Strip the bracing and forms off a newly poured basement, haul the heavy, moisture laden, filthy 9 ft sheets of plywood out of the excavated area up a slippery ramp and drop on the trailer.