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. 

I own some small multifamilies in Concord and High Point, NC.

I am currently a senior in high school nearing graduation and have a growing passion for learning this industry.

I look for low crime rates, good schools, high rent to value ratios sometimes as high as the 3% rule. 

As a general rule of thumb, no one ever lends for less than the rate of a high yield savings account.  

(I also would like a loan that doesn’t require a high down payment).