In my opinion, I would not take the advice you received regarding using OPM is you have no experience in investing in real estate.I would also not look to be a private lender for several reasons1) You are better off putting your money with a corporate bond / CD and get 5-6% with little risk compared to 10% to 12% with much more risk given today's market conditions2) You won't be able to retire getting interest income, which you said is your goal.

If you already come with the experience (i.e) r/e background experience, don't need one.

You did not underwrite this on any of your offerings though, so you're speaking from direct experience not by observation. 

I think I'll just look at this as a learning experience for how I operate going forward and take my chances on having it appraised as is.

As a seasoned real estate agent with five years of experience under my belt, I've had the privilege of guiding numerous clients through their own investment journeys.

Does anyone have any experience / can advise on the process in each of these counties?

I have some single family rentals north of you in Delray, happy to share my experiences if you want! 

As for taxes, I'd recommend connecting with a CPA or tax attorney who has experience with rental properties held in LLCs.

If so, what has your experience been? 

It sounds like you are already getting great experience in STR management!