Adding that extra unit will reduce your risk since you are adding another income stream to a property you already own.

We have a phenomenal airport and they continue adding routes as the population here is growing, but there are still no direct flights from Denver to Myrtle Beach in the offseason...

It really depends on how much value you're adding to the property.

Columbus has become a major tech hub in the midwest with large companies like Intel investing $20 billion, Amazon investing $3.5 billion, Google building 2 new data centers: one in downtown Columbus and the other in right outside of U.S. 33 in Lancaster.

Granted, the owner was a total slumlord and refused to repair anything, but I'm confident that a large part of the issue with the bugs was caused by the tenants themselves. 

An appraiser is unlikely to give you added value for converting the bedroom into an STR.

We are now adding fees on top of the 10%, not fees for us but Airbnb has been tough lately charging us cancellation fees so the owner will have to absorb them as well.

Some grants are deferred payments, or will be an additional amount added on to your mortgage. 

Added new plumbing, new electric, new windows.

You don't want to rely on a single large employer to the extent that if they close up shop the whole town goes bust.2.