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.
it will not update and if it does it might lock your phone and you will not be able to use it.
You need to be plugged into iTunes to update the latest software and it isn't always recommended for those that are Jailbroken.
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.
You ll get for not jailbroken . Factory unlock will sell for more.
You dont
You can get free ringtones for a non jailbroken iPhone 4, 16gb online at mobyware.net.
No, you can even unlock the iPhone when Jailbroken.
Yes but your iphone has to be jailbroken and have Cydia.
Yes you can.If you have an jailbroken iphone you can get it for free
no
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