PerfectHybrid
as far as I know, if you order online with that email etc that's it - they won't ask you to verify anything etc. This isn't like a covert operation or anything; it's allowed.
As for paying off your bill, I doubt it. Unless it's nextel, but even then it'd be a pain I bet.
It's easy to xfer your old phone number though - DESPITE what they tell you. I had to call 3 times before I got a CS even willing to do it. The first two told me it'd take 2-4 days blah blah blah. And finally I got someone with two brain cells and she said up to 4 hours. It was almost instant btw.
The "vision" package that comes with sero is basically everything. Any and all internet, email, mms, and now sms included. It also allows EVDO able phones access to the faster network, although I thought that was what power vision was for
The only thing it does "include" is tethering as far as I know, although people still do it without getting caught as long as you're not like using torrents or something.
As for phones - just start the sero process - there'll be plans to select with phones available.