Verizon: what's the "exchange" policy?

[mlevin77]

I'm on Verizon and eligible for a new phone (I've had an HTC Apache XV6700 for years now). I want to get an Imagio, but trade it in if an Omnia II or Leo show up soon. What's the deal -

1) what's the best way to get it? simply order it from the VZW website - $199 (2 year contract)? or do I call them and order it that way? do they apply some sort of "new phone due" credit and can they charge it right to my phone bill if I call them?

2) what's the exchange - can I exchange it in 30 days if the Omnia II or Leo show up? how does it work?

thanks,

Mike