I have had one rental property in the past, so limited experience, but have a lot of research tools to help with questions.

.*** Debt is a tool that will bring you down unless you have it under complete control.Read these again.

Or, your credit score is 615 and not 620 however I see that you have paid your past landlord on time and I will accept your credit based on your past rent histories.The intent of the legal requirement I'm sure is to keep landlords from arbitrary unjustified excuses as a selection tool in discriminatory matters, it's a consumer oriented requirement (surprised by Texas).As to credit, I would select your risk tolerance level, might be a credit score of 620.

Utilize the key word tool to be informed about it.

What tools do you use while narrowing down zipcodes?

Costs fluctuate like the stock market so some of the guides / tools out there are using pre-pandemic values which will sink you in a heartbeat.Have you looked in local REIGs to see if you can find a local flipper or contractor that you could shadow on a few walk throughs? 

Many tools mentioned are for people with more rentals and more experience.You need a REALTOR to help you understand the market, find properties, write contracts, negotiate, and stay out of trouble.You need a lender.You may need a Property Manager to help you manage the property, but that depends on your time available, willingness to learn, ability to deal with people, and other factors.You will eventually need a handyman, plumber, electrician, and other professionals, but you can definitely wait until they are needed.

When looking for "deals" in regard to real estate there are countless ways to analysis and pick apart a deal.Aside from the obvious ones such as the BiggerPockets tools, what other tools do you use for analyzing potential deals or an area that you're looking into?

The thought process is that if I like the deal today, I may love it a few years down the road where I can refi (whether I cash out or not) under better terms to reduce debt service.I'm sure this is the kind of thing I could spend a lot of time trying to build in Excel -- am wondering if anyone can direct me to an existing tool that might help with this.

Both of these organizations have Find An Advisor tools.