Recycling my previous advice, for starters.
Anyhow, let me try and address each point individually...
Politics: At a very generalised comparison, you could view our labour party as a vague democrat parallel, with the liberal party more republican, I guess.
Australia's political scene is overdue for upheaval, because both party leaders are abysmal. Julia Gillard, labour leader and our current prime minister, is a treacherous opportunist who basically turned the party against former PM Kevin Rudd. Her proposed carbon tax will probably do her in. On liberal, Tony Abbott is even worse. I usually lean towards liberal sensibilities, but I would never vote for Abbott. He's a flip-flopping moron whose unfit to lead a country.
Voting is compulsory for all Australian citizens.
Laws: Nothing terribly radical here...
General life: Incredibly straightforward. Australian life is so uncomplicated, I wonder how other countries get by. Australian culture is laidback and good-humored. Yes, you will get lots of comments on your accent. Yes, expect many ignorant assumptions.
Job prospects: Depends on your qualifications and experience. Getting started can be difficult, but if your resume is good, it's a big benefit. The job market is very competitive.
Buying cars: Can't think of too many complications. Brand new or second hand?
Etc.: An unfortunate truth: Melbourne is not a good city to be alone at night. I'm not talking ghetto here, but there's a clear abundance of shitheads looking to mess with innocent people. Mostly kids, you'll find. Frankly, I felt safer at night in England, Paris, Canada and the USA.