Or to just his since I have not had any communication with the other tenant that was on the lease?

Those are buyers not renters unless there is some other circumstance.I think you are right about supply....apartment construction is just about to come to a halt and unless interest rates drop in 1/2 probably won't see that pickup for a while. 

Can you help me to understand why Columbus might be a location to consider other than multiple solid 1% deals?

As others have alluded to, buying larger units or a house near the beach is a better play. 

We have an existing mortgage (backed by these 2 lots and 2 others) and given the increase in appraised value there is no need to pay anything back to the lender when selling the lot.

Look at buying my first investment property (probably a house in the 100-150k range) and begin looking for a tennant.I can imagine there a lot of different theories/ideas with what one could do here--I am just curious to see what other people think.

I'm looking for other investors in the Calgary & Okotoks, Alberta area.

Lets say its $270k and you are financing $220k and it takes a year at 12% thats $26k in interest plus other costs etc.

One who is active still and recently did a case study write up like this is Don Konipol, the other pops on every now and again and did a BP episode many years ago Aaron Mazzrillo so search those two names and read some threads.A more likely scenario is not what you mentioned as the ever growing note/value deal, at least not as outlined.

Did you work with any real estate professionals (agents, lenders, etc.) that you'd recommend to others?