One more thing, only the 8Gb version is getting the price cuts from O2 and T-mobile, if I remember correctly. That can also mean that the 8Gb version is being phased out
You can switch off the iPhone, but normally you let it sleep. It checks your email when it "sleeps" and that is why an unlimited data plan is bundled with the iPhone everywhere it is sold. Airtel plans can be used all over the country without any additional charges. It was a real help to a friend of mine who went to Chennai. He said the "Locate Me" feature in Google Maps, really rocked in Chennai.