Sorry AP, I hadn't even seen this thread. Apologies that you haven't received many responses from down here, I can't speak for others but I don't check Off-Topic too often.
I'm not too good on your temp scale, but from what I can interpret you prefer a colder climate? Newcastle is north of Sydney, and from what I know of Sydney weather it is pretty good - verging on the warmer side. And yep, you got the seasons right. I'm from Melbourne, and down here it starts getting warm in November and remains that way until around March. Cold months May until around September. General temp range in Melbourne - in summer we'll get around 5 or 6 days in the 40's (Celsius), averaging around 30 - in winter, rarely gets below 2-3 degrees, usually around 10-15. Used to rain a bit, but we are in a drought right now.
We sorta talk funny apparently - I never truly realized this until our US trip earlier this year and couldn't even order at Subway without being asked to repeat myself. Be prepared to speak very slowly and gesture a lot to make yourself understood. About the only crew I could easily communicate with were the Texans, and maybe that was because I grew up on a farm.
We drive on the wrong side of the road - or you guys drive on the wrong side of the road. Whatever, it will spin your brain the first time you have to deal with it.
I agree with all the points that Charlie raises above, I think he has summed up the situation pretty well. Unfortunately we are a bit divided as a nation right now, probably more so than at any other time in our history. We have a deeply conservative federal government that has aligned itself heavily with the Bush government and US policy, and this has upset a lot of people - particularly in relation to the Iraq war and the Kyoto protocol. Having said that though, I'd say the overwhelming majority of Australians will be extremely hospitable and welcoming. Most are smart enough to realize that current trends in world politics can't be directed towards individual citizens - and besides anyone who has to endure the flight down here deserves a little respect!
Anyway, if you do make it down here to Oz make sure that you come to our FSAE comp (in Melbourne in December). And if you do, make sure that you drop in to RMIT and we'd be glad to show you around.
Cheers