You do not Jailbreak iTunes; you jailbreak iPods and iPhones.
Yes.
No
No, use redsn0w.
No
No you can download apps without jailbreak, but you will be able to download apps that have been disapproved by apple if you have jailbreak.
that's right
i believe it is because your ipod has been bricked. This happens when you jailbreak with itunes running. To fix this restore and then re- jailbreak with itunes closed. Have anymore jailbreak questions email me @ arobinson410@gmail.com
Yes, you can "Undo" a Jailbreak, by going into iTunes and Restoring your iPod Touch, or iPhone.
It is safe to jailbreak it on JailbreakMe.com But it is suggested you back up on iTunes first.
You can without but the easiest generally do use iTunes.
To get rid of the iPod jailbreak, restore your iPod through iTunes.