It looks like you're new here. If you want to get involved, click one of these buttons!
As far as visa requirements for Australia, it all depends on how long you plan on staying in the country and whether or not you plan on working. The simplest Australian Visa to get for a US Citizen is an ETA (Electronic Travel Authority). The visa is valid for one year, allows multiple entries, and the ability to stay in the country for up to 3 months at a time.