They have to first prove misconduct. You don't have to prove you are innocent of wrongdoing.
If you have been unfairly dismissed go to the Fair Work Commission.
depends, if the business is a small business <15 employees then the test is reasonable belief. see small business dismissal code.
if you have been suspended from duties, i suspect that they will invite you into a meeting to get your side of the story. make sure you bring a support person as witness.
unless you've been terminated in which case you have 21 days to lodge an application to the Fair Work Commission.
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