Once you unlock the iPhone it becomes essentially the same as any other phone. Once you take out the SIM card provided and put in your own you're charged for and receive the same features you had on your original phone. If you have a Pay as You Go SIM card then you're still forced into those...
No, Apple is being very careful about exchanges lately and won't take any excuses that aren't on a preapproved list of known issues supplied to them. (In most cases. If it's obvious it's their fault they MIGHT take it) Chill out about your tiny little dent though. You're going to get a lot of...
That's the result of the phone unplugging during download. What you can try is to reset your phone and try to update it again because sometimes it isn't finished upgrading yet so it just ends it. That should bring your contacts if they were backed up on your computer. If they're not backed up on...
I suggest you use ZiPhone. If you have already then you might want to make sure you pressed unlock AND jailbreak on it. I used this program and I had no problems at all. Best of luck