If you buy an existing home, they will inspect and may fail a septic system if it does not meet current standards, even if the system is working fine right now. Schools are what you make them. An administrator should be happy to show you around. The key to quality education is parent involvement. The more interested you are, the better the education will be for your children.
Jurisdictions overlap in Texas.
County and City boundaries have no bearing on school district boundaries. So learn what the school boundaries are before looking for a home. Schools all over Texas are crowded. Accept the fact that your children will probably spend some of the next year in a portable classroom. Consult your Prudential Alamo Realtor for the distinctions between the districts.