Not sure if this is best practice for the investor (because from the books Ive read here I haven't heard a single person say they waited 2 years), or in the best interest of the mortgage company?

Maybe, but it certainly is not a very practical business model right now. 

It's a basic banking practice.

A simple, generic "pest control" clause would sufficiently cover all of these.

Lending practices were drastically tightened after '08 which has subsequently lead to better underwriting and better debt securities.

Mean time, she is practically squatting without paying rent and we must resolve this mini crisis because we are loosing rental income for couple months now and hefty eviction/court fees as the days drag on. 

They're going to have a mix of market-rate, affordable housing, a practice arena for Washington's WNBA team, a hotel, and a homeless shelter.

It's standard practice for all legal notifications to be in writing, preferably by regular mail, but these days email notification may suffice.

To do it right, there would be rather high compliance overhead, which necessitates a certain magnitude to absorb.I think it's not a bad idea, bit not practical if you have a few hundred thousand. 

The hard part is identifying the bottom.If you do pursue buying rentals I would try to do it through seller financing,  that way they are non recourse loans or if you go through traditional lending practices keep your loan to value amounts below 60%.