"Billabong" is an aboriginal word for a wwatering hole (Sorry, I don't know which tribe calls it this, there are several tribes each with their own languages). A Coolabah tree is a species of tree. It's very shady.For other Australiana type stuff, you can check out my website. It's at http://expage.com/kettrickensjamdrop
I don't have an explanation of Waltzing Matilda actually means, but there's all sorts of stuff there. Also, if you ever want to talk about Banjo Patterson and his works, I'd be happy to help you (me being an Aussie and all..and darn proud of it!). You can email me at ladykettricken#hotmail.com anytime.
Finnabhair