yes,the 5.0.1 jailbreak came out !
Official EasyRa1n Unlock/Jailbreak iPhone 4/4S iOS 5.0.1Chat with our AI personalities
You jailbreak the firmware.
Yes you have to jailbreak
At this moment you can't jailbreak the dsi. Refer to dsibrew.org for updates on it though.
The reason behind the jailbreak is sometimes theft of software (PS3 Games) and that is illegal.
No, when the SNES came out, Pokemon wasn't invented yet.