I would rotate testing a couple(make sure it's a large enough size to gauge results).

We have parked outside units to figure out the comings and goings from time to time, but truth is it doesn't really matter and life is easier when you don't monitor it and let it raise your blood pressure. 

They’ll use tools like infrared cameras and moisture meters to trace where the water is coming from.Also, since mold is suspected, consider having mold testing done.

They are friends moving for a year to test new waters, and we all expect that next year they will not move back and I will buy the property (and add to my STR portfolio). 

You got lucky that the top was showing and that made you get it removed and tested.

.• The current code requires an STC rating of 50 for Lab Tested Systems and 45 for Field Tested Systems for walls and floor/ceiling assemblies for apartments.

Instead, the STR loophole uses tests like:Did you work 100+ hours on the STR and more than anyone else (including cleaners or managers)?

.- AC in my unit that we lived in went out twice while there in year 1, maybe year 2, spent about $800 to have it pressure tested (lesson learned here most home warranty companies are garbage and do not cover testing your HVAC so idk how you trouble shoot it without testing it, but the testing and refrigerant are not generally included) chased a leak for a month and ended up having them replace the line-set to the system for $1400.- AC in the other unit went out a year or two after that, was not a big issue, just needed one of those jump starter things, and some refrigerant, but was about a $800 fix to get it done on a weekend.- Roof vents were not secured correctly, so that lead to a leak into one unit when it shifted, was about $750 to get the vents secured and have additional ones added to bring it up to proper number.- Still need to get the gutters done, they need cleaned and one of them doesn't drain as it should.- Main water line and entire meter popped off the main supply line and had an unimpeded 1" water line dumping into the basement on mother's day, was about $1400 to fix, and basically an afternoon of waiting around for city and fire dept to turn on/off water at curb. 

From there, a conceptual site plan and work towards all entitlements that will be needed, inclusive of LDP and Geo testing for the dirt.

They don’t account for the blood, sweat, and capital required to get there.They Encourage Speculation: Focusing on cap rates can lead developers to bank on future market compression (lower cap rates) to justify a deal.