Property managers and agents can be really helpful as well as they’ll give you insight into the market and could have some opportunities for you down the road.In the meantime, try researching the areas you're interested in.

Don't discuss the mold with him because he obviously didn't provide evidence or the opportunity to remedy the situation. 

Look for off-market deals, seller financing opportunities, or even house hacking a small multi-family with an FHA loan (3.5% down) if you plan to live in one unit.For creative financing, explore seller financing, subject-to deals, and lease options.

I was given the opportunity to appeal the decision, and provided proof of new ownership and property management, but Air BNB is maintaining their ruling to delete the listing for being duplicated. 

The rental market demand is still extremely high and there are a lot of value add opportunities, you just have to be willing to put in the work.

If the land is in a suitable location, this could open up opportunities for developing 2 homes or even selling off one of the lots, which could lead to a good profit.

I guess my question is, should I narrow my focus to one REI strategy or keep it broad and analyze each opportunity individually?

There are still a lot of opportunities for BRRRRs so I'd encourage you to keep your eyes open.

Underwriting sponsors and their opportunities can easily be a full time job if it is done properly. 

This seems like a huge untapped opportunity.