If you have a severe software issue, restoring will fix it. If you have a cracked screen and want to send it in for repair, restore it and they can't tell it has been jailbroken (but you'll loose the jailbreak, obviously)
Jailbreaking your iPod doesn't magically make every app free. What it does is allows root access to your iPod/iPhone allowing you to customize it and install other apps that aren't on the apple store.
No duh. What gave you that impression?
whatI was saying it because everyone in this thread is like "PIRACY BANBANBAN"