I am paying additional taxes on the rental income, as well as business fees.I assume this is the part of the tax code we're referring to: https://www.irs.gov/taxtopics/tc415, and this is the line:"A member of your family or of a family of any other person who has an interest in it, unless the family member uses it as their main home and pays a fair rental price."

Part of what makes Bigger Pockets such a great platform.I'll reach out via pm with some additional resources.

There are programs that will also auto-flip to owner's account to avoid shutoff and these resulting situations.In addition to @Nathan Gesner great advice, you should check with an eviction attorney about how to legally keep the tenant from returning to occupy the property or pursuing eviction as necessary.

Additionally, I am seeing a lot of STRs now being advertised as MTR or LTR.

In addition, the equity I have in the home represents the vast majority of my nw, so I feel like I'm not well diversified. 

- Aside from the following: Condo fee, tax, home owners insurance, hurricane insurance (is this in addition to home owners insurance)?

It really depends on how long you plan to hold and what your long term goals are with acquiring additional properties.  

Additional information: rZoning permit from 1/16/1956 with a variance granting this as a 3 family unitI have no building permit saying this allows this as a 3 familyI am asking for any advice specifically for Philadelphia, PA.

In a few years I was doing some big commercial RE syndication deals which is now what I focus on, in additional to some JV opportunities.

If you are referring to ocean front structures, there are additional CAMA rules in place that go above and beyond the flood rules for renovating a structure located within or forward of the oceanfront setback.