The ABS should have everything you would ever need and will definately have a time series back to 2000 (and it will be available free of charge).
This does not mean that the ABS will present the data exactly how you might like to view it. For example the ABS does not produce a time series of CAD as a percentage of GDP, however they produce everything that you need to compose such a time series.
I think the RBA's website is particularly useful because the ABS has a lot of data that may not be relevant and finding a good series is like finding a needle in a haystack. The RBA produces a set of statistical tables in its monhtly bulletins. These are available online and are a synthesis of statistics from the ABS and occasionally other sources. But the benefit is that they are presented in a more simple manner (which makes searching easier) and they are only economics statistics so they are more relevant.
The ABS and the RBA deals with domestic information. They arent really concerned with what the standard of living in nigeria is for example. So you are not going to find international information such as HDI, or PPP. You need to check the OECD website for that, however obtaining a time series that goes back to 2000 may not be available for free as they charge for some of their time series (although current data will usually be available).
Be carefull when using other sites because it is highly unlikely that they are the original creators of that data. They might only reproduce the data. So for example if a website summarises Australia's current economic performance using data from the ABS and publishes it online, you shouldn't credit that website for your data. You should credit the ABS.