Clean the refrigerator and stove spic & span. 

And because we have 8 units, is there a way to use a shorter time span to at least determine the short-term rental viability of a neighborhood?

You will absolutely pay more in Aug/Jan then spring/fall.I generally agree that you don't fix what isn't broken however, the ages of those units you mention sound way beyond the average life span. 

Spic N' Span anti bacterial and refills mainly.

@Darryl Jennings 30 day span for the credit pulls to have it all be one- but I always tell my clients that a lot of credit pulls for a mortgage may make an underwriter wonder why you’re shopping around so much and if you’re having issues getting approved.

The span between the foundation wall and the column looks pretty long for (3) 2" x 10"s?

If I amortized the renovations over a ten year span, they would approximate to 10% of the 45k rental income.  2 of the bathrooms were redone, studs, tile, and water supply lines. 

Many can just take this info and assume it's a great deal BUT if most items are 10yrs beyond life-span, well I am betting the seller is laughing all the way to the bank on it.

The life-span for concrete/steel multi-family homes is given at 37 years!

These are the percentages, derived from the facts--hundreds of tenants spanning a period of many years.