I have known people secure a rental whilst still overseas, just a bit more paperwork need is all. But, the quality of rentals here can be appalling. I certainly wouldn't want to sign a rental agreement for a year without seeing it first.
No, you don't need to be employed, but it helps! You will need to show you have money to cover the bond and rental.
Put in your application and paperwork online and tell the agent that a friend of yours checked it out for you. As for not being employed, I was in the same boat and I secured a place by paying for 3 months rent upfront.