"Do you know the vaccination rules/exemptions?"
I don't know the exact vaccination rules. I am pretty sure that there are 3 reasons one can exempt their families from vaccinations and all 3 are accepted in Texas. At the same time, the authorities like to keep track of who has exempted their children from vaccinations.
I handle the situation by homeschooling my children so that they don't have to sign any slips to get by in school or anything like that. The only time the issue would come up is if we wanted to travel internationally or if one of the children became sick and had to be taken to the hospital.
Good luck–and let us know if you move to Texas.