You could try advertising in your local paper. You could list things for sale by item or have a garage sale.
Or, if you want to do online there's always Ebay. Plus, there's another website that's just like the classifieds (not auction):
http://www.tradingpost.com.au/HomeFor giving things away there's charity bins, freecycle (online site) and always the garbage dump if necessary.
As far as what to do when you leave, since you're on a temp visa you should be able to take your super contributions with you when you go. So I'd look into that. I would check with the tax office to see if there's anything you need to do there.
Aside from that I would check with whatever province you're moving back to in Canada to check on health care. I've heard sometimes they don't like to cover you until you are there for several months. Although I think by law that could be challenged. Either way, something to look into. I can't really think of anything else that you need to do. Except for maybe look into ways of transferring your money back to Canada.