How Much Will It Cost??

[nooter99]

I have a family plan, one of the secondary lines is eligible for an upgrade. If I buy a droid trough a third party (Wirefly, Amazon, etc.) when I receive the phone can I just activate the new phone through the VZW website and then just add the unlimited data plan through the website aslo? or do I have to call them direct to add the data plan? the line I'm upgrading is a dumbphone with no data package. I assume my bill should go up by only $30 right? Is there anything else I need to do to get the phone up and running? Thanks for any help.