Yes it is. It is the codification of the castle doctrine under the penal code. If you don’t believe me (An attorney since 1991 and licensed to practice law in three states including Texas) try the Texas State Law Library under the Texas Penal Code Chapter 9, Subsection D:
https://guides.sll.texas.gov/gun-laws/stand-your-ground
“Yes it is. It is the codification of the castle doctrine under the penal code. “
No it isn’t. The doctrine applies only to your habitat, not other properties.