I can't comment on Africa.
Australia and New Zealand will require a work permit/visa. I'd check out the Department of Immigration (Australia) for information there. Use the ones with .gov.au as they're the official sites.
From what I have been reading in the Dununda forums (a good source of info for Australia and New Zealand) it's a bit of a mixed bag. As ever, getting your first job is tough and you have to have an element of luck with a shed load of patience.
Most new guys head to places like Kununurra, Alice Springs and Kakadu. Those jobs will be mainly scenics and charter in C206, C207 and C210s. Some folks go to the Torres Strait.
It's been over 20 years since I did it so my info may be dated and so you need to check the current state of play. It was fun but hard work. I got a lot out of it, stuff that can't be taught etc.
