I cross-check the BP Calc results with the "HOLD Sheet," a spreadsheet calculator from "HOLD," by Gary Keller, et al(Strongly recommend the book if you're wanting to do more buy-and-hold investing).

There is also a river that borders the town.  30 pound catfish are common. 

It would depend on the size of the estate how exactly it should be setup though.Alternatively, just buy a lot more malpractice insurance and cross your fingers nothing too crazy happens.

The thought crossed my mind about “what if I tried to accelerate growth moderately by keeping half my reserves in the stock market, in index funds?”

You can cross collateralize with both the new property and your old properties. 

Get closer to the Bloomfield border and you're getting easier tenants while still attractive price to rent ratios.

You also need a good real estate attorney that will dot the i's and cross the t's for you.

Is crossing Benning Rd from Carver/Langston to Kingman Park worth an extra $1500 a month in rent, or crossing Georgia Ave from Petworth to 16th St heights, worth the same rent bump, or Crossing from into Takoma fromt Brightwood or Riggs park worth nearly $2k in additional rent?

Try Cross Country Mortgage though! 

I have to say I'm interested in your cross-country jobs/investments.