Estimate cost of living
Depends on which state you are: I can give an overview for Victoria precisely Melbourne.
 
Single Private Room in a shared house: 150-180 depends also on how close you are to the CBD,closer to city more expensive.
Bills: sometimes included in rent others shared equally among the # of occupant.
 
But set aside around 75-100aud per month for (Gas/elstricity/internet/water) if house sharing
Food: Single person I find 30-50aud per week is enough then again some weeks you buy more or less.
 
Refer to coles.com.au or woolworths.com.au for common food prices
Mobile: cheapest with unli call and text to any network plus decent 1GB data a month is 19.90
Public transport: Daily cost 8.25 I think unlimited rides (bus/Train/tram) but if you buy a 30days pass around 145aud unli rides as well.
Of course additional cost would be private insurance if not yet PR, entertainment cost etc...
Hope that answers you question