I finally tried out on trip to north carolina, side by side with garmin nuvi. Drove my wife crazy having two gps units talking to me

Anyway, couple of questions:

1. On iPhone4s Verizon network, running on 3G signal, how much data does it use for a couple of hundred mile trip[s]?
2. I assume it's quite normal to drain the iPhone battery? On the way down, I had it plugged in but on drive back from Washington DC to CT, almost drained battery after 4+ hours.

Thanks