altought I am very jelaous of you Aussies having summer while I had to face a Hail storm today
i will try to help you out.
The German pre is SIM free. For 20 Euro per month for 2 years or 481 Euros at once it can be useed with SIM cards of all major German providers. However, currently the German Pre has no option to manually enter the internet settings of your provider. This will probably be fixed by the End of November.
The menus can be switched to english, the QWERTZ keyboard is a chellenge. Please keep in mind, that German und english keyboards often differ in the layout of special keys like ?-, etc. Also, you will probably have no need for the Euro Key
The initial setup creates a profile with Palm, I donīt think it makes any difference if a o2 Germany, vodafone Germany, t-mobile Germany SIM-card or your australian SIM-card starts the internet conncetion for connecting to Palmīs servers. The firmware update can be done using a Wireless LAN too.