Will an iPhone bought in the US work in australia?

So i'm going to New York soon and want to get a new phone while i'm there but was unsure whether the phone will work here.

KEY INFO:
1) i plan on buying my phone from the apple store not on a plan through a US provider.
2) I'm on vodafone at the moment but may change to optus

I have read other forums but haven't come to a complete conclusion
QUESTIONS:
1) are phones bought from the apple store locked in anyway
2) are phones bought at the apple store purchased with a plan?
3) is there any specific model of iPhone i need to get?
4) Will it work
5) are there ways to jailbreak it to make it work

I don't want to have to pay for a plan and then cancel it and unlock it.

Please include info for 5s and 5c models as i'm unsure as to which i will get.

If you need any other info please just ask i should respond promptly.

You would need to get one that has world coverage, which most do! Thing is that if you are legitimately charged import tax on your return to Australia then your purchase could be more expensive than if you'd bought it locally. You also would have no local warranty!

Phones bought "off-plan" are not locked.
Apple stores can sell you phones that are on a plan or ones that are off plan!
You need to ensure with the sales person that the phone will work on 850,900,1800, and 1900 GSM bands!
It should work, however if it does not you have no local warranty!
Jail Breaking an iPhone is not the easiest thing in the world!

I would say no but you'll have to ask the apple employee

Key word being 'unlocked'. Just go to the Apple store (no where else to be certain) and buy an unlocked phone. True, it'll be pricey but it will be open for global use and not 'locked' to any specific carrier. Even after inserting your sim card it will stay unlocked. Curious though. Why not just buy an unlocked iPhone in AU? More expensive there? Best luck.

Here are the prices:

Buying an iPhone in US: http://store.apple.com/...e-unlocked
Buying an iPhone in AU: http://store.apple.com/...e-unlocked

These are what you should be comparing. The $99 price tag comes with a 2 year contract

As you may see the phone unlocked in US is cheaper than Australia US$549 vs AU$ 739

Q: Will I phones bought In America?
A: It depends completely If the phone is locked or unlocked. It has everything to do with the SIM not the physical phone. Some phones bought in say India may come standard in the wrong language however you can watch youtube tutorials of how to get them to English.
I recommend the I phone from Amazon. It takes approx 10 Business day's (14 days) However you save over $200 by ordering on amazon and over $500 If you bought at a store.
This is the link
http://amzn.to/...to/1sOXM6N