Do I have this right? Calling plan is one cost (e.g., 450 minutes for $40 or whatever it is). That's for voice phone calls, yes? Then there are plans to cover text messaging on top of that? Then another cost for a data plan, which will allow me to use email and the web, right? Then another cost for tethering that lets me use my iPhone and my data plan to access the net with other devices. Is that about it? Many thanks. I'm hoping to find out before I buy one tomorrow morning.