Ok so my Husband and I finally got ourselves new phones. We've never had a "data plan" before and not really sure about the whole thing. So a couple questions that I have are: 1. I know we use the date by downloading the app but once we download an app, are we incurring data charges when we use that app? 2. We have the Xfinity app to check email...are we incurring charges on that? Or only when we open the app to check email? 3. We have the Facebook for Android app...same thing, do we incur charges on that? And if so (on all 3 ?'s) how much is usually used up? We have a 5G/month usuage limit...by just basic browsing the app market and checking emails/fb will we be ok each month? Now we have wifi at home...if we change the setting on the phone to wifi will that take the place of the data charges? Any help would be greatly appreciated!!!