Upgrading to 4.0
I have a 3GS 3.1.2 jailbroken. I never got into the scene, and as such never really did anything after I jailbroke it. Anyway, I'm a tester for a dev. I want to update to the 4.0 beta. I have a few questions about this process.
First, can I just download and install 4.0 and expect it to patch up and remove my current jailbreak? I don't mind losing the jailbreak, since I never utilized it. Does this cause problems or "flag" my phone as tampered, or just a clean install and fix my jailbreak?
Alternately, should I do a full restore on my iPhone before the upgrade to ensure there are no problems? That seems fairly time consuming, and I'd like to avoid it if possible. Also, since I've never done that before, does iTunes retain my contact info? If I did the "delete all content" restore, I am hoping iTunes keeps that info for an easy restore.
Sorry for so many questions. Hopefully, someone can understand that mess of text and help out.