It’s not accurate to use median household income to measure affordability.

Requirements are less stringent, but interest will be “higher.”

I also purchased a laser tape measure so I can verify bedroom and other measurements quickly. 

Again, that sounds great measuring it using that worthless number with a % behind. 

Bank statement (less stringent personal requirements), DSCR (look at rental income vs mortgage amount), and some other outliers.

I  used Home Depot's Web site to select the doors I wanted and also used the Homewyse website to get a second set of numbers, and they came both pretty close to each other at $1800 products and $1300 labor.I then contact Home Depot to get a person on site to inspect and take measurements, and a couple days later I get an estimate with two sections: Customer Pickup #1 for $2695, and Installation #1 with $0 total.

Questions, or measurables that I can quantify, are things like:i) cost per square footageii) no. bedroomsiii) distance from public transportWhat are other measurables around property purchases?

I would say effective age of the property might be a better measure.

If renting, what other measures would you do to ensure your property is protected (yearly inspections?) 

Here's Jacksonville's measureables:- home prices 27% below the national median- gross rents .3% above the nation median- 19% more home price appreciation than the national average since 1991Look for a market with similar numbers if you want to maximize your 5 profit centers.