You would be best to download the death certificate for $20AU for that information. We only have access to births to 1920.
You might find his arrival in Australia here:http://recordsearch.naa.gov.au/Scripts/PassengerSearch.asp
Check out New South Wales BDMs for possible marriages:http://www.bdm.nsw.gov.au/cgi-bin/Index/IndexingOrder.cgi/se...
You might find birth or marriage notices in digitised newspapers here:http://trove.nla.gov.au/newspaper?q
A search of Ancestry's Australian electoral rolls might find other people living with David who may be relatives.