I would suggest having the phone unlocked if you're wanting to use the Android phone in Europe, just to save from the international costs with Verizon.
I'm not sure you would be able to forward the verizon number to a prepaid phone, but I have no idea when it comes to that. You should be able to sms, you would just have to enter the country code for the states.
What I was originally going to do was take my storm and grab a sim card from one of the european carriers for it, but I was mostly going to use it to contact anyone that I would be contacting in Europe, not necessarily to contact friends and family back here.
Hah... on second thoughts, this post doesn't seem to be all that helpful....