I recently just purchased a iphone 4 and was curious about how there 1yr warranty works. Like does apple cover the battery of the phones wear n tear and am i able to just bring it in later down the year and have them replace it? also lets say i have this "temperature" screen pop up and say the "White" iPhone 4 drops am i able to exchange it for that color considering they could be the same price as the black model. thanks.