After spending about half an hour figuring out how to transformer my MP Megatrons (with extra care not to break them), I have now replaced the temporary "borrowed" photo of their Gun Modes in the first post.
Both photos are now ours for future reference, and can be used with permission.

I also got an email today from Customs, which pretty much says what I already had... so just SA and ACT left to reply.

Please note that the toys are regarded as replica firearms and replica firearms have the same import permissions as firearms for the purposes of the Australian Customs and Border Protection Service and restrictions and permissions for importing and exporting apply.
To bring a firearm into Australia, it is necessary for the importer to obtain a 'Form B709A: Importation of Firearms - Police Confirmation' from the Police Service of the state of Australia that the firearm will be imported into. Visit this link for a list of contacts for the police in each state. The link also supplies all the relevant fact sheets outlining the requirements for importation http://www.customs.gov.au/site/page4372.asp

You will need to obtain the B709A before you may import the firearm.

Please note that the Firearm will need to be fully declared on importation into Australia and Customs Duty/GST may be required to be paid.