Yes. It is compulsory by law for all eligible Australian citizens aged 18 and older to enrol and vote in referendums and federal elections.
If you are already on the electoral roll for federal elections you DO NOT need to enrol again to vote in a referendum
A referendum can be held at any time, it does not need to be held in conjunction with a federal election.
Yes, there can be multiple questions.
Yes. The results of the Referendum must be carried out by parliament and are legally binding.