It's free for me, the only fee is for my tenants when processing payments. 

Never be afraid to bring up and discuss any and all downsides so that you and your partner are both aware of each other's though process on one-offs.Hope this helps!

Communities such as Berewick a huge master planned community is mandating that you can only own 1 rental property in the community.

Houston is a little expensive, especially when combined with current rates but there are some BRRRR deals that can work with decent ARVs...just as a quick example, here's a ranked list of properties by BRRRR in Houston - there's a few that potentially make sense but not a huge amount of choice.

I realize there's no way to capture everything, and learning is a continual process, but it feels helpful to me to have a working "cheat sheet" of information to study and reinforce important concepts.

I've been wondering if I should become a real estate agent and start the process of getting my license at 18?

only if it doesn't work ha    Lots of great feedback and advice here all comes down to your values and after that your goals work on those first to slow your process down and really get clarity on what you are actually trying to accomplish.   

Who has the best terms and who processes quickly, my neighbor is selling soon and I want to pick it up before it hits the MLS.  

Finally, I would get started on the FHA/VA certification process early.

I am about to begin the process of acquiring investment properties with the intention of using the BRRRR method.