The Australian Bureau of Statistics released data from the 2011 Census yesterday. The good news is that you can access community profile info free and online. Click on the above link, the "Data and Analysis" on the left, then choose QuickStats and go to Advanced Search. Type in your postcode or whatever.
Here's an interesting summary of changes in religious affiliation - Land of Many Cultures.
"Multiculturalism has won the battle for Australia. The 2011 census reveals that Australia has become a melting pot of races, with more than one in four Australians having arrived here as migrants, while almost one in eight has Asian ancestry"
"For the first time, most Australians aged 25 to 34 are no longer Christians."
The Age online has a a data summary here.