When you start opening up old houses you'll find problems that need to be addressed if you want to deliver a high-quality product to the end user.

HML have high holding costs.  

You can also build a relationship with a good local agent and ask them to run comps for you, or in certain situations like selling a high-end home to a friend off market I’d recommend just paying for an actual appraisal.

I'd highly suggest coming to one of the local meetups to network with other locals that are interested in doing this.

If you can't keep control of your personal finances, you are highly unlikely to succeed in real estate investing.

While evaluating potential investment properties these past few weeks, I have realized that the average rent in Austin is comparatively lower and due to high interest rates and property tax, the outcome is mostly negative cash flow. 

Virtually every mortgage broker* will use the FM Selling Guide for determining eligibility, or you google "fannie mae underwriting guidelines" for high level details.

Yes, the timeframe between getting the new property and selling the old property is high interest and 3 different payments (old property mortgage, HELOC payment, new property mortgage).

The land is mostly forested with a year-round stream running through it - it's beautiful and private and was largely unaffected by the recent floods as it sits high up and consists of large hills.

I would highly encourage you to think about your family first.