Hello! I really want to unlock my iPhone using the Dev Team method but I am actually using OS 1.0 on the iPhone with a lot of stuff already installed. My questions are:

1) if I upgrade from 1.0 to 1.2 (the version required) do I lose everything?
2) if I upgrade using iTunes 7.4.1 (2) is it going to work?
3) when I upgrade then I need to jailbreak the phone again? What SW do you suggest considering I'm on a MacBook Pro (Intel)?

Thank you guys.