It was just my wife and I for most of it, and I don't think I'd try to do it again (doing all the work myself while working a full-time job and a part-time job) even with just the two of us.

Higher interest is their hedge against the chance that you default.That said, there are basic protections that can be put into place besides just "your word", and a lot of them have already been listed so there's no need in restating (mortgage, alternative asset backing, etc,). 

I've got excellent credit at the moment and a job with six figure income (however much lower after taxes/student loans/primary mortgage), would this help gain what I want with a lender?

The building has a parking lot with no cover and a brand new 30-year roof.

I am a successful business owner for two other companies and a single mother of two young boys that I homeschool. 

I also sold my own personal duplex in Kalamazoo (west side of Michigan) for $59,000 that was renting for $1,425 per month and a bungalow sale pending that is rented for $835 a month for $30,000.  

My parents bought and held two triples and a house that they rented in the Waterville area when I was going up.

We are older and my daughter is grown and we are looking to have enough passive income to live in and a little extra.

That is the cost of owning in a co-op AND a condo.

Those property's NOI would sell for the same cap rate and a cost to cure adjustment would be subtracted below the line.Finally CAP RATE IS OF ABSOLUTELY NO USE AT ALL FOR SFR'S AND SMALL MULTI'S!