it will not update and if it does it might lock your phone and you will not be able to use it.
yes. the current update is 3.1.3 and to update to it you have to restore you iphone, update it then re-jailbreak it. but at this moment in time this is not an jailbreak for firmware 3.1.3.
You need to be plugged into iTunes to update the latest software and it isn't always recommended for those that are Jailbroken.
it's not yet compatible so wait to see if there is an update and then it will be compatible
Upgrading an iPhone will update the firmware (the iOS) and will therefore remove the jailbreak. If you wish to stay jailbroken, it is highly recommended to not update until news of a new jailbreak arrives for the upgrade.
if its already jailbroken than you will need to unjailbreak it (take the jailbreak off) then when its normal ;go to itunes go to and click update and cancel it because it will erase every thing than push shift+restore and it will update .then when its done install your jailbreak program:blackra1n,redsn0w,etc.
It depends, studies have shown that the 4.2.1 update has sped up not only the device but also battery life. Depending on if you are Jailbroken or not and how many apps you run in the background.
Yes. It's also free to update payed apps, that you already bought.
yes
you must restore itouch then update. Sorry!
Not without erasing the jailbreak.
Yes, but it will no longer be jailbroken.
Your not supposed to restore or update anything after jailbreaking a phone.. it messes it up. They should have told you that when you got it jailbroken