I am really confused with so many variants of iPhone 6/Plus. In short my questions are: 1. Can you use iPhone 6/Plus from TMobile/Apple-sold TMobile on ATT network? Any hardware difference? 2. Can you use either ATT/TMobile specs iPhone 6/Plus on Verizon? I know one is GSM and another is CDMA. What about vice versa? 3. Are all the new iPhone 6/Plus' have EXACT same hardware inside except software difference? 4. Can I purchase Verizon iPhone 6/Plus with full price at Apple Store to use on ATT? Thanks!!!