Additionally, do companies tend to first test your skills through residential deals, or can someone get directly into Commercial deals? 

I went into it thinking “I can probably get $1,100 per unit which pencils out to a good deal” (not exceptional but good).To test the waters I listed the pictures and description (without the exact address) on Facebook marketplace for $1,275 (which turns it into a great deal - mathematically).

Stress test your exit at 6.5-7%, 30 yr arm.

So it is a good contract, tested extensively, and most people in the industry including your title company is familiar with it. 

Make sure you research the FHA loan limits and the "self sufficiency test" that any 3-4 unit will have to pass before you dive in. 

We attempt to evaluate drainpipes by flushing every drain that has an active fixture whileobserving its draw and watching for blockages or slow drains,but this is not a conclusive test and only a video-scan of themain line would confirm its actual condition.

@Leslie L MeneusGet a soil test Check the elevation, utility connection and Verify city zoning

I figured I'd test out the calculator using the numbers from my first investment property that I'm about to refinance.

The definition of fair market is along the lines of: The price a ready willing and able buyer will pay, acting in their own best interest, being informed as to market values and conditions.So by definition, market value is (almost) reduced to what a buyer is willing to pay.Add in multiple offers and one can logically argue, the accepted offer was bid up to market value.Contrast this with refinances where there is no test of market value, there is no purchase contract to establish value......in this cases, I often find appraisals come in low.

You can also ask this question a contractor that would test fire systems.