There are a lot of hidden pitfalls that you need to be aware of.
First, as far as I know, if one is producing pornographic material then the only place that itr can be done legally is within the ACT if the scenes are explicit (X rated). If it is just nudity (no sexual interaction) then it is fine to produce anywhere (such as photography) so long as you are not outside other laws (you couldn't do it at a shopping centre while it was open, but you could do it at the same shopping centre when it was closed so long as you had permission from the owners, blah, blah, blah).
Second thing to be aware of is that (currently) if you want a .au domain (of any type) then you need an ABN and a registered business name that is in keeping with the url that you want.
So if you wanted the domain sexyaussiegirls.com.au then you would need a company named sexy aussie girls pty ltd (or something very close). If you had an existing photography company called Billy's Girly Calendars then you can't get sexyaussiegirls. You could get billysgirls or billycalendargirls or billygirlycalendars and so on.
This may be changing soon, not too sure on what is around the corner. But there is talk in webmaster forums about this requirement being relaxed. Note that if you wanted a .com there is no such restriction.
The third thing to consider is hosting. Most webhosts have some very specific "no porn" clauses in their terms and conditions. There are a few adult-specific website hosts, but they tend to be few and far between and generally more expensive. Do your research before you buy any hosting.
Getting the girls is easy if you have loads of cash. If you don't, then it'll boil down to your charming personality and how well you can sweet-talk the girls. You'll also want to cover yourself legally if you want to make money from the footage since the girls (and guys) will need to sign contracts and provide you with acting releases granting you the rights to use their likeness.
If you don't cover yourself, then they may verbally say "yes, I'll perform", you put them up on the site and then they can take you to court for not providing royalties and invasion of privacy (depending on what type of footage you generate).
You also are required to keep USC 2257 compliance records if your material can be accessed by people in the USA. This is something you cannot get around, unless you use a geo-blocking IP system to prevent people in the US accessing your site. Or have a team of really expensive lawyers on call.
Everything becomes much more simpler if instead of being a producer of pornographic material you simply become a distributor of pornographic material. The difference here is that you are not creating (and hence, not starring in which I think is half the attraction for you) the material.
A good example of this is Truth or Dare Pics where the webmaster asks people to send them material rather than creating it. This works as it is a bit of a niche site catering to a specific demographic. Plus you are covered legally as if any material is put on the site that should not be there (such as the "star" finding out their ex-boyfriend submitted it and they demand it be taken down) can simply be removed.
You'd be able to claim that you accepted the material in good faith and that now that it has been shown that the material was given to you out of good faith, all you can do is remove said material. They can't sue you for it (unless it turns out that the material contained underage persons, in which case you would then be in for a world of trouble).
So short answer is "yes" you can make legal porn in Australia and the long answer is that you need to jump through a few hoops and put a bunch of cash down up front to do it properly.
And even if you think you are doing everything properly, you can still miss a step and get caught out. Look at what happened to abbeywinters.com, though that one looks like it is blowing over quite quickly.
Bloody unreal.