I live in New Zealand and no one has a jailbroken phone; I'm running a Vodafone sim, on pre-pay and I just got a 3gs; so I'm running it stock-standard and I know fuck all about jailbreaking; so what happens if I jailbreak - can I still text and call; will jailbreaking affect my network use? And use all the same features, and what about my non-jailbroken applications and itunes music, does it wipe them or what?
What features does jailbreaking remove; and realistically what benefits does it give.
Can I "lock up" my phone again, return it to normal; un-jailbreak it? - if I undo jailbreaking does that still void the warranty?

- I'm not the biggest tech kid on the block and have a lot of questions so if anyone can help that would be wicked, also what's the best software to use to jailbreak? - I'm running OS 10.5.7