I am looking into buying a new phone which I can use abroad (Europe) with local carriers.

I would like to stay with Verizon as my US carrier.

I am looking for a clear answer (ideally from Verizon) to the following.

1) What steps must be taken to use one of "Verizon's" cdma/gsm phones abroad on a gsm network with a different carrier?

2) Which Verizon phones may I simply add a 3rd party sim card into (when not in the US) and use for all the same services I have here - specifically voice/text/data?

I have read reports of Verizon customers having difficulty using their cdma/gsm phones abroad - and sometimes being restricted to voice/text (no data).

I've read a bit about APN data.  But rather than relying on 3rd party sites.  Where can I get answers to these questions from Verizon?  (In lieu of that, answers from this community are certainly welcome.)

I feel I am not getting clear information from customer support.

Perhaps this information exists somewhere, but I cannot find it.

Any help would be great.  Thanks.

(Specifically, I am thinking of the GalaxyS4 and maybe MotoX phones. But these questions above are general.  Finding something written on Verizon's site will give me more assurance when/if I purchase a phone from them, than slightly varying reports from their customer support chat-team.)