Ive got a web adress where you can lease Mi-8s and Mi-17s, I believe they can arrange crew, maintenance, ect. Let me know if thats any help. Only condition is that if you do end up working it in Sydney, you gotta let me watch!
As for Russian helicopters operating in Aus I believe there was a Kamov operating out of Bankstown for a while, and I have been told another one is on the way out.