Although Australia is a polyglot nation, with over 100 languages being spoken by those sections of the population who have emigrated there from all over the world, English is the official and by far the most commonly spoken language.
Australians tend to put directness before diplomacy and therefore can be considered quite blunt on occasions — especially by people from those cultures in which the majority are wary of speaking plainly for fear of creating a negative emotional impact upon the people they are talking to. Directness is cherished in Australia and failure to say what you mean and mean what you say can be mistaken for evasiveness and even hypocrisy.
It is important not to be too self-promotional when presenting to Australians. A hard sell approach can often be misconstrued as bragging and can provoke a very negative response. Remember that people do not like to make out that they are better than others — the same probably applies to products and services. A factual description of issues will be far better received than a more hyperbolic approach.
Australia is one of the very few cultures in which humour is all pervasive in business situations. Not only is humour acceptable in all situations, it is expected in all situations. Never underestimate an Australian senior manager because he or she uses humour at what you might feel to be an inappropriate time.
First names are invariably used in all business situations in Australia. It would be very unusual to call a business contact by their surname. Similarly, educational titles play relatively little part in business situations (other than in the medical or academic worlds.)