I have add 1Go for Europe. Where can I see the travelling data usage for this 1 go ? If I go over 1 go the connection stop or i will be charge for extra data ?
You will see it on the main page of your package for that line.
From experience, I can tell you that there is a delay of a few minutes for the update of the data consumed.
If you exceed the go, it will stop your data services, you will not have an automatic billing.
By the way, even if you're out of data abroad, you still have access to your account from your phone, so you can buy another add-on if needed!