You appear to have posted 3-4 essay questions one after the other...
Is there any you actually want to do / have an interest or more knowledge in?
In terms of international affairs, Doc Evatt had a huge role in setting up the UN, and we played parts in wars in Asia, in Korea, Malaya, Indonesia and Viet Nam, and later on, in peace keeping missions in Cambodia and Namibia, and then our involvement in the Iraq wars...
For Indigenous Australians, finally getting citizenship via the 1967 referendum meant they gained a whole host of rights, and these where followed by things like the Wik and Mabo decisions of the High Court.
For an overview of Viet Nam, there are other threads: http://www.reddit.com/r/AskHistorians/comments/2dpvau/why_did_australia_get_involved_in_the_vietnam_war/
Perhaps if you ask more specific questions, or give more of an explanation of what you want to look at, you will have more luck, as it is quite hard to answer such broad questions, and these essay questions are designed to give you leeway to research something you find truly interesting...