For example, you spent $100 in advertising the unit to get the first tenant.

Of course, we obliged and though we didn't have any formal system of accountability, I think that the time he spent with all of us helped establish a new standard for what was normal.

Outside the box specials get the attention of renters as well.  

I've spent 10s of thousands of dollars with PropStream and I can't seem to get any support on questions outside of their basic how to's.

Other than that it seems like you are checking the boxes you want offloading the house for an amount you are happy with and getting to move on, the real question will be will this keep you from moving on like planned.

What else do I need to do, to ensure I’m checking all the boxes for this type purchase?

The reality is, it take a long-term mentality (it could take several years) and a very focused buying box.  

The money you've spent so far is all tax deductiblealong with depreciation of the property.

In my experience, CPAs will fill in the boxes and it is up to you to ask questions on how to best take advantage of tax incentives. 

I will have spent about $8k on paint, flooring and labor for the two units.