A:
Wi-fi only means you have internet where you can get a wireless connection such as at home, or a Starbucks. If you purchase a data plan, you have internet wherever you are. If you are just using it at home or where you can connect to free internet, skip the data plan. If you use free internet at Starbucks, etc., it is not secure, so don't check bank accounts or shop on line. For what you want, wi-fi only is fine.