Ok, I had to reformat my computer and I obviously lost iTunes and EVERYTHING.

I just have a few questions, if I download iTunes off apple's site, and I plug in my phone, is it going to sync all my stuff off my phone and put it onto my computer? Or will it whipe my phone clean?

Also, question 2. Which I am sure has been answered a million times.... Do I need to upgrade my phone to get MMS, or is it another kind of update where it does not require going to 3.01?