New Zealand was never a state of Australia. New Zealand was briefly (for one year: 1840) a dependency of the colony of New South Wales in Australia, but this was before either New Zealand or Australia were regarded as separate nations.
The Commonwealth of Australia was established in 1901. New Zealand declined to become a member, and became a British Dominion in 1907.
Because Australia doesn't want to pay for New Zealand.
There are many places you want to visit in Australia. New Zealand is an island many people choose to visit.
if you want
You have to be 18.
because they had already colonized Australia so they decided to colonize the country next to it.
ANZAC is the Australian and New Zealand Army Corps. ANZAC was a collaboration of the countries of Australia and New Zealand and formed in 1914. They were active in battles between 1915-1916.
I could find one at most New Zealand and many Australian ports. If you want shipping schedules contact port authorities or vessel agents.
Age of Majority on your state
No, not until the child is 18.
Maybe , maybe not. If they contact the other states authorities and they decide they want you you will be held and transported to that state.
No, minors are not allowed to choose.
The US wanted help from any nation; but only Australia, New Zealand, Thailand, South Korea, and the Philippines responded.