Preferred Form
Australia is a relatively safe place to carry reasonable amounts of cash and currency is easy to exchange. Otherwise most travellers will have no problems using major credit cards as they are commonly accepted for transactions in most places.
Tipping
Tipping is becoming more widespread in Australia, principally in the major centres where there's been more foreign influence. However, it's certainly not expected in any restaurant. You should tip in a restaurant (not in a simple café) if you feel you have received exceptional service.