Most of the time if you go to the "general" and the "about" you'll be able to tell.
Yes, you can put music on a jailbroken iPod Touch.
The fourth generation iPod Touch has not been made yet, and there are several other iPods with a fourth generation, so specific information of the iPod is needed to know whether it can be jailbroken or not.
you cant
I don't now a other way to get cydia of but the only way I know how to take cydia of is to restore your iPod touch
Yes, the iPod Touch with the 2.0 software can be jailbroken.
yes restore it
I guess
Once jailbroken, the iPod Touch's one year warranty is void.
A jailbroken iPod Touch is certainly legal. However, the act of getting every app in the App Store for free (the ones that require payment) is illegal.
No...
it is battery
Not without erasing the jailbreak.