I can assure you that a 25 hour course to obtain a license is not close to being sufficient to underwrite these notes.

Is a high school diploma sufficient?

If you try buying a triplex or fourplex using FHA, the property will have to pass the self-sufficiency test...otherwise it wouldn't qualify using FHA. 

While the 2% rule may help you determine if the property cash flows sufficiently, it does not help you determine the property's value.

Escrow funds sufficient to make staying past the rent 'term' financially negative enough that they'll be sure to move out. 

People with sufficient income will move to a safe suburb or to another city, further decreasing the area's average income.

Rent will certainly differ however it may not be sufficient to make up the difference in the cost of a mortgage.

The premise sounds all great and all but it all assumes they have you have sufficient positive cashflow to constantly keeping your daily balances low (rents/invoices/receipts/etc coming in through out the month).How has your experience with the strategy been?

If you are in a dry climate where temperatures only reach the '80s in the summer and cool off at night, then window units are only occasionally needed and sufficient.

KC has had torrential downpours too and we're getting water in basements left and right (mostly the properties we bought in the summer and fall, we thought we had done sufficient grading, we were wrong).