FWIW I'm a current Pit owner and have had multiple dogs on the breed ban lists over my lifetime.

I placed multiple  calls to them and they said if I called again they’d drop the deal!

You'll most likely have to do it multiple times.

Using criteria like price-to-rent ratio, pop growth, employment trends, and wage growth, relying on multiple sources (PropStream, Zillow, Rentometer, FRED) to calculate averages. 

Always get multiple lenders working for you in the due diligence process!

If you stay in one market for multiple investments it may take you a bit to find this particular inspector.

The yard looked like trash, plumbing stack leaks and multiple water heater leaks.

For example, should we focus on acquiring one high-quality property in a strong market, or would it make more sense to spread the investment across multiple lower-cost units in emerging areas?

If someone came to me looking for money and was trying to invest across multiple asset classes as different as the ones you are interested in, that would leave me extremely weary.

You can get multiple rental properties for under the 400k range here.