Our son is disabled. Ios 7 and 8 have a feature built in called apple's switch control that will allow disabled people to use their devices with a switch to maneuver around the screens with something called a Tecla (http://gettecla.com/). Anyway we are looking at buying a used IPad (not mini) and want to know what is the 1st Ipad that came out with IOS 7? Also if we purchase a used one and it is not IOS7 can any ipad be upgraded to IOS 7 or 8 and what size memory should we get to accomplish this. Totally new to Apple world so please bear with us. Thank you need wifi but not cellular. Thanks.