I actually found one of Lance’s books on Amazon when I was first browsing around.

Amazon sells readers that work as well as any, I imagine.

I am a sound professional who has built several recording studios and a sound wall between 2 tenants on a house hack I have most contractors have no clue how to do this correctly and definitely not any drywall contractors I have ever heard of. 

Is Amazon placing a new distribution center near your rental market or did the largest employer in the community just lay off half the work force?

There's so many catalysts for population and job growth (Intel, Honda, Amazon, Nationwide Hospital, etc).

I owe 6 studios and I’m currently renovating them to do short term rental. 

It may make sense to "overpay" for a property that won't cash flow initially if you know that the value of that property will skyrocket in a couple years (say, because Amazon is building its new headquarters a bus stop away, or you're a geologist who knows there's probably oil under that grass).

I don't know if it is called "efficiency" when you have a studio within the unit (without a new construction outside the property) B) Or, do you apply to the city for converting the duplex into an official triplex (replacing the door with a dry wall)?

Columbus has companies like Intel, Amazon, and Google investing here. 

Specifically, there's job growth (Intel, Honda, Amazon, Nationwide, etc) and the population is growing (unlike Cleveland or Cincy).