I'm planning to buy a new sim card to get this thing going through the 2g phone. But if a borrow a friend's 2G, will I have to reset any network settings or any others? I just want to give it back to the original condition as when I got it from him...
Have your friend backup the iPhone to his computer, because you'll HAVE to restore the iPhone from your computer to activate it. Then when you're done with it, give it back to him and he should be able to pop his sim card in it, restore from backup, and be back to normal (assuming he actively uses the phone)