hahah.
South Australia probably has beef with everywhere else, not just Melbourne. rightly so, too: the place is full of Brit-Aussies and they are far too easy to make fun of. that said... i like Adelaide. nice local music scene, though not as full-on as Melbourne. I recall that the zoo is pretty cool too... but I've not been there since year 9.
ETAs are recorded and linked electronically to your passport details. when you turn up and they scan your passport, the information comes up and they know you're cool.
enjoy OZ, but watch out for drop-bears.