u get administrative priviliges like u can over clock your phone, install custom roms etc...for more consult xda-developers.com
By jailbreaking it.
Jailbreaking will void your iPhone's warranty.
you cant?! jailbreaking only exists for ipod touch, iphone and ipad
no the creators from the dev team are good at what the do and create a great product that wont hurt your device.
You cant without jailbreaking it.
Jailbreaking is free.
Jailbreaking a phone is partially legal and partially illegal. I have a post regarding this http://www.techlucid.com/2013/11/is-jailbreaking-illegal-or-not/
yes it is absolutely legal
Yes and it works pretty well for me
Nothing. All it does it trash your iPod/iPhone and do you know what happened to mine... It stopped my iPod completely.
It is okay to jailbreak your iPhone 3g. The only downside to jailbreaking your iPhone is that you will loose your Apple warranty.
Yes by jailbreaking your apple device