Hi Cliffy. You're familiar from the VapourArt thread. Even though I've moved on to squonkers, I'm so sad they have closed. Truly great mods.
There is no problem coming in and out of the country as long as you follow the general rules on the carriage of batteries (spare batteries protected from short circuit and in carry-on baggage only ... that sort of thing that applies everywhere). There is no federal law prohibiting e-cigarettes or nicotine, and customs is federal.
Within NSW and the other states, there are laws prohibiting the sale of liquids containing nicotine, so you won't be able to buy any liquids with nicotine. Since you DIY, I assume you will bring enough with you anyway.
There are a few vape shops in Sydney, but they all sell liquids with zero nicotine. In general, we import nicotine separately and add it to the liquid in the privacy of our own homes
Theoretically, even the possession of nicotine is probably illegal under state law, but don't let that frighten you. We all vape quite openly (including members of the police force), and no-one has ever been prosecuted. It's just selling that is a big no-no.
In NSW,
vaping is not covered by the clean air legislation that prohibits smoking in some areas (though vaping in a car with a child under 15 in the car is illegal). However, most indoor places will send you out to the smoking areas. I generally don't vape in 'no smoking' areas - it just makes life easier.
Does that cover it? Just ask if there are any more questions ... or if you run out of liquid when you're here. Enjoy your trip!