well you need to unlock it and activate it using the pwnage tool and then get the best data rate sim card you can in france. i think you should be able to use it as a touch and wifi etc. without a sim card in, but if your there for 4 months you may aswell get a cheap sim card whilst there.
however, if you are going to get an orange sim card in france you dont want to choose to activate when using the pwnage tool. orange is the official carrier of the iphone in france and it will activate itself in itunes. if you choose activate in the pwnage tool then get an orange sim card, you will get no service until you repwn/restore the phone.
you can use the pwnage tool etc. whilst in france, the power of the internet
