Another Western Australian chipping in.
Tips: I’ve never done it - even for dinner - and no-one I know tips regularly. It hadn’t even occurred to me, before I got to read a little about the tipping habits of US Dopers. It’s certainly not expected nor necessary.
Pokies: Hey, another reason to come out west: no pokies! Mass gambling (sports betting and lotteries aside) is confined to the casino. There’re no pokies in pubs - a good thing, IMO. (It’s a recurrent political issue, but for the moment the voices of the social welfare groups have outweighted the complaints of the Hotel Association.)
Issues: The treatment of asylum seekers in Australia is a topic to be avoided at all costs. This is the touchiest of isses in Australian at the moment. There’s an outcry even when the UN dares to comment, so an American tourist would best be advised to take the 5th, so to speak!
Word choice: “route” pronounced “rout” makes us giggle like schoolgirls. “Root” and “fanny” are also another funny words, as is the name “Randy”. Speaking of fanny, “fannypacks” (1) have a funny name; and (2) are unfashionable and will mark you as an American tourist from a mile away. 
"Miles": Funnily enough, most Australians have a pretty good understanding of your crraazy Imperial system. I’m a comparative young 'un, but I’m more inclined to use inches and feet to describe the size of an object. The older generations are even more comfortable with the old ways. Miles are well understood by all. ('Course once you start getting into fathoms and hogsheads, then you’ll lose us. :))
Casual insults: Don’t be offended by these. In my experience, Australians take ourselves much less seriously than others. Consider “bastard” and “wanker” to be affectionisms.
Local beers picks: Sydney - Tooheys Extra Dry, Tooheys Pilsner. Adelaide - Coopers Sparkling Ale. Perth - Swan Draught, Little Creatures, Redback. Queensland - XXXX (just for the local ‘flavour’ ;)). Hobart - Cascade Pale. National brands: Crown Lager… and VB if you really must. Even better, try out the local microbreweries. Finer than anything mass-produced, IMO.
Local wines: Hell, go crazy and try as much as you can! It’s cheap (especially with the current exchange rate) and there’s some fantastic stuff. OTOH, wine-in-a-box was invented in Australia, but please don’t be tempted. The decent bottled stuff is just too good to pass up.
(What naturally leads me to) Drink-driving: I’ll spare everyone the safety spiel, but I’ll note that random breath tests are constitionally legal in Australia. This is a major policing issue down here (thankfully!).
Finally, Western Australia! I’ll repeat tritone: it’s well worth the trip out here! Consider this is a state the size of Western Europe with the population one-sixth of that of London! It’s all worth seeing, from the hot and sparse far north down the massive western coast, to Perth and to the cooler forested south-west. This is a beautiful and unique place.