Hi -
Resellers licenses are only required by US sellers in order to pay sales tax (see here Link hidden: Login to view).
There is no sales tax in Australia, so you won't need a reseller license. However, you will probably need to get an ABN and register for GST if your earnings are over $75,000.
Just ignore the requirement for a tax ID if you are contacting US suppliers. They will not require one from an international buyer.