Welcome to Geekdom! ESN cloning is a big no-no here.
http://forum.ppcgeeks.com/showpost.p...2&postcount=68. In theory, any CDMA phone should work on VZW. It's a matter of whether or not they will activate it on their network. As for your ROM question, that is dependent in what phone you choose. For example, I cannot use a VX6800 ROM on my Treo 700WX. What phone you should go with is personal choice. Fifty different Geeks will give you 50 different answers. I've had my Treo 700WX for 18 months or so and likely hold onto it 'til it dies. On the other hand, I know there's users that couldnt wait to get rid of theirs. If you're looking for something fairly inexpensive, you can find some of the older models, i.e. VX6700, VX 6800, Treo 700WX on eBay, if you wish to go that route.