Or is it common knowledge?

Prior knowledge issue, yep.

Someone here with local knowledge of the tax sale laws can chime in. 2) were these “tax lien” sales or “tax deed” sales?  

@Evan Polaski Thank you for this knowledge, I am definitely looking to shadow someone here in Houston, there's so much I want to learn about before I just jump in.

I also give credit to Bigger Pockets for helping us with our investment strategy, knowledge, and confidence when it comes to rental properties.  

I would highly recommend you connect with and follow @Garrett Brown he's got a wealth of knowledge about STRs! 

Ten of them, $200 and you'll have 20K worth of knowledge to put in practice.PM me if you want more info/assistance. 

I have done several evictions on my own in the past simply to gain knowledge.

I've been educating myself through books and podcasts on topics like sourcing off-market deals, deal and property analysis, creative financing, and title reviews.My fiancé is an architect that works with GC's and structural engineers to design homes ensuring they are functional, aesthetically pleasing, and safe- which I hope will help me navigate this space as I grow my knowledge.

This will also help when marketing the property for sale or rent.At the end of the day your realtor is going to be more knowledgeable about the market you're in than I am, and how this would help your property, but based off what you've said I think it'd be a wise investment.