[lost_]

1) Sure, that's what I used, but if your question is about the price, that depends on your plan. I have SERO with unlimited data.

2) Check with iTalkbb if they allow BYOB SoftPhone. But, if not, there are plenty of VOIP providers that do.

3) Data only.

4) Just configure it to connect (menu, register or menu, re-register) it to your VOIP provider's server and port number, using your user name and password (you can opt to save it so it would auto login). The SIP port # is usually 5060.