Legal Question in International Law in Alaska

Re: Australia Law

It is almost certain that your child is a U.S. Citizen. Probably nothing has to be done to make him a citizen. But to get documentation of this (i.e., a U.S. passport), you need to present proof that you are the parent and that you are a U.S. citizen by birth, and potentially proof that you lived in the U.S. for a certain period of time. This is generally presented to the U.S. embassy in the country of his birth. Details can be found on the State Department web site.

As for visitation, you need to consult with a lawyer in the location that has jurisdiction over the matter - unless the custody/support order was entered in the U.S., you probably have to go to Australian court for that.