We have lots of stickies and threads in the Hacking Section and various sub-fourms dedicated to the advantages of jailbreaking. Please take some time to review them, but start here -
http://www.ipadforums.net/ipad-hacking/2838-jailbreaking-explained.html
As regards IOS6, there is no jailbreak for it yet on the iPad and there likely won't be for some time yet. Monitor our sticky here -
http://www.ipadforums.net/ipad-hacking/89458-official-ios6-jailbreak-status-thread.html
Methods for jailbreaking the iPad are always listed here -
http://www.ipadforums.net/ipad-hacking/24377-jailbreaking-methods-ipad.html
Jailbreakers cannot normally update to the latest version of IOS as a jailbreak needs to be discovered, developed, and released. This can take anywhere from days to months. You also cannot update a jailbroken device OTA. You must "restore" a fresh copy of IOS on there and then jailbreak and restore your previous backup.
Jailbreak apps and tweaks can be backed up separately using a solution such as PKGBackup. See here -
http://www.ipadforums.net/jailbreaking-hacking-tutorials-how-guides/60220-how-use-pkgbackup-safeguard-your-jailbreak-apps-settings.html
Hope that provides you with a starting point...