They may focus more on the property’s income and your assets rather than your personal DTI.Negotiate with Existing Lenders: It’s always worth a shot to negotiate with the lenders who pre-approved you.

Transfer of Leases and Tenant Information•Review the existing leases to ensure compliance with local laws and assess any terms that may need to be adjusted.

In my experience, tenants who are paying $300 in rent tend to react more negatively to these things and I've had issues with getting them to leave peacefully, but very broad strokes. 

The only problem I now see is that I got sidetracked from my plan and now I'd like to pivot and adjust my routine to my interests and become the investor friendly agent, helping new and existing investors get their first or next investment.

That is probably cheaper to do and if the existing laundry are just hookups in a basement an upgrade that might give you a similar result in terms of tenant experience. 

Peace of mind will comes from dealing with right deal and right people and right area, and not from high CoC returns. 20% CoC is not worth the headache it brings if deal or tenant or area turns out to be bad. 

If a renter wants to extend for a few months their stay beyond the initial lease term, will I be a) required to extend and b) at the same rate as their existing rate?

Why do these exceptions exist, then?

You are looking for financing that doesn't exist in the current market.

They go around the country partnering/acquiring existing property management companies.