They finally came back with the following:“At this point we would just need you to apply for a “Special Inspection” at our office for visual “certification” of the existing structures.”I am curious what this sort of “visual certification” entails.

I've gone through other threads on this forum about the legal ramifications of dealing with pre-foreclosures in MD without the proper certifications, and I was curious about MD regulations for marketing.

Estoppel Certificates:Do you ever submit an estoppel certificate to tenants in properties with so few units? 

As of this writing, the license itself is called a Transient Occupancy Tax Certificate (TOT).

I have also found that it's important to have them sign estoppel certificates before closing, regardless of property type or size; especially if the owner supposedly doesn't have leases.These days I'm happy to walk if an owner is going out of their way to not let me talk to tenants or get estoppel certs/existing leases.

Is there a certification that i should look for?

It's possible to have a legal basement unit, but usually basement units are not legal units so I'd strongly urge you to ask the building department (NOT tax assessor) the number of legal units on that property, if possible get a zoning certificate confirming that number, etc.

I suppose they could withdraw the Certificate Of Occupancy, or if one was never issued, they could declare the property 'unlivable' and force you to get it permitted and brought up to code.What a mess!

I am currently a property manager for a large real estate brokerage and I would like to know if anyone could share some insight regarding the worth of obtaining the CPM certification.

Here is a listing from Mpls' webpage, a bedroom must be 70 square feet: https://www2.minneapolismn.gov/business-services/licenses-permits/construction-permits-certificates/building-requirements/habitable-room-definitions/  The definition doesn't list 7 feet but anything under 7 feet would probably be looked at as a closet by most people looking to live there.