Canberra is similar to Oberon, maybe not quite so cold, but similar.
The only issue with hot water on a frozen windscreen is if you have an existing crack in the screen - hit it with hot water and just watch it run!
My current ice scraper is 12mm thick UHMWPE with about a 60° edge on one side. I've broken credit cards, and even thinner UHMWPE. Had the 12mm one for over 15 years now so I think it works.
Covering the windscreen and windows with a tarp is a good thing if you can be bothered. I usually can't. Don't cover them with newspaper, because if the newspaper gets wet before the the sky clears and the frost arrives you just have a reinforced layer of ice on the windscreen. You'll enjoy that!
If it has been wet weather or you've driven through puddles before parking the car and expect it to get below freezing over night, leave the vehicle in gear (if its a manual) or Park but leave the handbrake off. The handbrake can freeze on and you will need copious quantities of hot water splashed onto the wheels to get them to release... or wait till lunch time. It depends a bit on how much hot water you have and how hard the frost was.
Keep a camera handy in case you get some good patterns in the frost on the windows or if you get a hoar frost you might get some great crystal structures.
Be grateful you don't live in Canada and need fuel abd block heaters, etc... or in Siberia where you have to build a wood fire under the fuel tank and engine and around each tyre to get it all fluid/flexible before you drive off. -40 to -55°C would test my sense of humour after a while I think.
Al.