Australia and New Zealand use 240 Volts, 50Hz and have a unique style of power plug. While it might be possible to obtain an appropriate adaptor in Australia we would recommend that you obtain one before leaving home. An Australian power plug has two angled prongs and a flat earth pin.
Australia also has a unique telephone socket although most hotels probably have RJ style connectors instead. Some hotel phones do not have RJ plugs but you can readily obtain a suitable adaptor at local electronics stores, such as Tandy [Radio Shack] (in Gawler Place) or Dick Smiths (basement of the Myer Centre in Rundle Mall).
In Australia, like Japan and the United Kingdom, we drive on the correct side of the road (ie the left). Even if you aren't driving you should be careful when crossing the road and look right before stepping off the kerb.
Strange as it may seem when you first hear it but we are speaking English!
Tipping is not normal practice in Australia although feel free to tip if you think you got exceptional service. When dining with a large group it is normal to round up the bill to a convenient multiple.
Again the system of measures used in Australia is metric, although some people still remember the old imperial measures. This means that distances on the road are measured in kilometres and speed limits are in kilometres per hour even though the actual units may not appear. Liquids are measured in litres or millilitres (eg petrol [gasoline] is measured in litres while soft drinks (sodas) come in 375ml cans and 500ml bottles).