You don't need to get a TFN in order to get a job, they'll request this information when you are organising your payroll.
Are you planning to operate as a consultant or contractor? In which case an ABN is not necessary, it would be easier and cheaper for you to do this through an outsourced payroll company if necessary as you don't yet understand tax liabilities in Australia.
Either way, it's very easy to get a TFN. Go to the ATO website and it will guide you through... oh and if you are living in Australia for more than 6 months or intending to: You are a 'Resident for Tax Purposes' - Don't get slammed with the top rate 'non-resident' tax.
ABN you can't apply for until you have a TFN to link it...