just to say that yes it is still a public holiday even if the shops are open. i've checked.. im working the sat and get paid public holiday rates. in perth the sunday isnt classed as a public holiday.. which baffles me. This might help you with public hols in adelaide: http://www.safework.sa.gov.au/show_page.jsp?id=2483
also i grew up here, was sad when going to the uk that you didnt have easter saturday as a p.h. made that mistake once offering to work thinking it was time and a half!!