From what I've been able to gather, if it says "Extended Network" in Manage Connections, you shouldn't get billed extra, but if it says anything else... I'd call VZW customer support to really get a definitive answer.
Your phone shouldn't say roaming unless you go international is basically what I was told. If it does somehow, do a battery pull and wait awhile (he said 10+ seconds) and then power it back on. Should clear the problem.
As far as I know, there is no such thing as roaming within the USA, at least. But like it has been said, a call to vzw shouild square things away for certain.
ya under manage connections it says roaming at my cabin along with a little red triangle. fornow i just set data services to off when roaming but ill let everyone know when i get time to call verizon up.