I'm confused about the difference between unlocking and jailbreaking an Iphone. I'm currently with AT&T in the States but we're moving to Toronto and I thought I just needed to unlock it for it to work on a network in Canada? Is it necessary to get it jailbroken as well?

Once it is unlocked and with another network, will I still be able to update the software on it? It is version 3.1.3.

Also, will unlocking and/or jailbreaking the Iphone alter any aspect of it? Will it still have all the same features?

Can I still add apps from the Itunes Store?

Thanks for ur help!