Most were minor but the last couple were major fixes (air conditioning and leaky pipe).

Firewalls usually require two separate walls with air space between them and 2 layers of sheetrock on each side. 

None of the units share any air exchange or utilities, and the unit that is recorded to have had meth use has a completely separate entrance as well .

Yeah,They get to live indoors instead of having to sleep in a cardboard box on the sidewalk.They get the use of a furnace or other heating appliance rather than having to freeze to death, and many times an air conditioner so they don't have to be uncomfortable in the humidity and heat.They get to cook their meals on a stove vs a campfire.They get to not have to deal with rising property taxes, or maintenance on the home they live in.That and a lot more.All in return for a simple monthly payment smaller than many home owners pay to live in the same neighborhood.And many of the so-called "Poor" have this paid for them by the rest of the Americans who work and pay withholding taxes taken from their take home paychecks.Everyone needs a place to live, and in America this is how it's done, there are no 3rd world slums here.The so-called "Poor"  are not exploited by landlords.

For those that manage their own STR along with STR’s for others, is there a program that makes your life any easier, or does everyone just use air BNB?  

Positive tests are REALLY common and typically just involve a cleaning of the air ducts and furnace.

I literally walked to the train station every day and it was only a 90min train ride into Grand Central.

What is going on in Central Connecticut? 

Have  you been to the REI Central meet up? 

They may have them, they may not.As for vacancy rate on a particular neighborhood there is not going to one central statistical database that has this data.