The main house shares a front door, but the first and second floors are both separate units.

Hi Brian, I'm not too familiar with the Columbus market but I do have 9 doors across Detroit and Memphis.

How many properties/doors should I manage for Story to make sense?

It is different for the elderly couple who has lived in their house for 30 years and now has a large building constructed directly next door and wants to erect a fence that exceeds the max height allowed.

Closing the top floor vents in winter allows heat to rise, so the top floor isn't so hot while the lower floors are cold, or open the top vents in summer to allow the cold air to flow downstairs.And don't correct them when they use the "real feel", or "feels like" temperatures they have been reporting, just to make people feel as if temperatures are hotter than they have ever been.

A big issue however is the home next door.

In other words, that percentage will only rise (unless prices begin plunging).Existing home sales rebound, sort of.

I own 20 doors which provides nice income. 

They didn't care that the rising water was from a windstorm.

Today, 7 years later,  I have 37 doors and real estate is my full time job managing those properties.I doubt anyone can tell you exactly what course you should take… but if real estate is your goal, my suggestion is to go find your local real estate investment group that probably meets once a month and start rubbing shoulders with everyone there.