Is there a standard termination agreement a seller should use with a realtor in the state of Texas? 

The inspection requirements can vary, but properties usually need to meet their safety and livability standards.

We put in around $15,000/$20k worth of construction & furnishings to bring it up to Airbnb standards.

One tenant in particular that was a nightmare (we had to evict and learned some HARD lessons with house standards), which impacted another tenant who started also being difficult. 

Evictions cost about $1100 and then about a month of no rent and about 5 grand in rehab seems to be pretty standard from my experience. 

It is about 1300 sq ft, I'm leaning towards LVP throughout and a pretty standard kitchen update-white cabinets, granite or quartz counter tops.

You can see if you can apply and qualify for a loan through the bank but most banks will follow federal standards and guidelines which allow them to sell the home to Fannie or Freddie if they so desire.

One of the things that make "Agency" guidelines good is that they are standardized across all states so you will not find many differences in Conventional, FHA, VA, or USDA loans. 

Most PMC's will charge a lot more than the industry standard 8-10% of collected rents to manage a Boarding House - which is what you have. 

You seem to have met the standard of the statute since ypu sent notice to the last known address.