I am considering opening the cellular account on my AT&T 3G-enabled iPad. I understand that when I do this I will have access to AT&T wifi hotspots, but I am unclear whether my data usage at these hotspots is counted as part of my 2GB monthly subscription. Similarly, when I am at home and in range of my personal wireless hub (which is subscribed through Verizon, not AT&T) will my data usage default to the wifi hub or to the cellular plan, and therefore will it also count against my 2GB subscription. Obviously I would expect to use my home network without using up my data allocation in this way. Thank you for any guidance here.