OK, your VERY FIRST FaceTime 'call' from your iPhone to any number starts as a cell call so the system can register your number and add it to the Apple servers. After that, all FaceTime 'calls' are free. SO instead of making your very first FaceTime call to someone overseas, call someone locally or sign up for one of the many free FaceTime services that are available online. That way, you aren't having to pay for an international cellphone call.
After your first call, it doesn't matter whether your subsequent calls are international. local or otherwise.
No, you are wrong. Your first Facetime call doesn't need to be initiated by a normal carrier call.
Just go to Phone->Activate Facetime.
Wait for the Apple servers to authorise and register your phone number (which you can enter in the field above the activation switch), and there go you, facetime any of your contacts phone numbers of email addresses.