I am exploring the possibility of buying a STR - this would be my first time owning any rental property, so I have a bunch of newbie questions. 

There is never SE tax on rental income from LTRs. 

After all, they were headed that direction before I stepped in to buy their house in the first place.In 2023 and beyond, I think acquiring houses subject-to is a smart strategy, especially if you plan to fix and flip because you don't need to keep the mortgage in the original seller's name for very long.As for acquiring rentals, subject-to is also preferable as long as you can count on at least $300 + in cash flow (and have reserves for 6 months). 

My original goal was to buy 5 rentals and have them paid off by the time I retired.  

While I am not a fan of log homes or all wood interiors, that style still plays well here in the rental market. 

My first rental is a condo. 

There are some people "real estate consultants" who will give you detailed reports: if they think this is better for a flip, rental, what rents you could get, recommended repairs (not as detailed as an inspection report). 

Thus its best to talk with your CPA early on as many are not familiar with the regs under 1.469 for “transient” rentals.

And this is going to get really murky, because the owner claims that he had a long-term tenant, and that tenant was then doing the rental arbitrage deal.  

I do own a rental property in Texas and manage it myself.