One reason, ironically, that you've not had any luck finding a job is because you are not here. An HR person going through hundreds of emails is going to ignore those which belong to someone who isn't available for an immediately interview. Also, as I mentioned before, many companies don't want the hassle of sponsoring an employment visa. You are also up against local and Mainland jobseekers who may well have similar skills to you, nevertheless are likely to be trilingual (English, Mandarin and Cantonese). If they are local candidates, they will likely live at home and will be willing to take $10K pm for a salary. That's an amount you can't live on or get an employment visa for.
You have to stand out against the competition. Being here helps - a bit. Language skills help a fair bit. You have to ask yourself what makes you so special that an employer must employ you ahead of all the other candidates. Then sell that because you're not an especially outstanding applicant (sorry) when compared to the competition (again, sorry).
This is why I suggested the Working Holiday Visa. You can stay here for up to 12 months. You can network, network, network (a key component in finding a job here). You can work legally - perhaps an employer will love you so much that they decide to take you on and sponsor an employment visa. Heck, even if you just work at a bar, you'll have some free time for interviews as well as some cash in your pocket.
There is another thread here about someone having been here for 6 months job hunting without success. Your ninety days will go by so fast. And then what? Back to Australia a little less flush? Do a visa run to Macau and be become a little more desperate/broke with every passing day?
BTW, the General Employment Visa still requires sponsorship (1. job; 2. employer sponsorship; 3. visa), i.e. not a visa you get first (NOT 1. visa; 2. job).