The United States and Australia are both a party to the Visa Waiver Program whereby countries reciprocally agree to allow their nationals to travel to the other country without need for an actual 'visa' per se for visitation purposes. As such, a US citizen can travel to Australia with only a valid US Passport (that would need to remain valid until after their return trip).
If, however, you are going for purposes other than to visit (Immigration, business, study, etc.) you would need a visa. Also, if you have a criminal conviction in the United States (this usually also includes DUIs) you would be criminally inadmissible and would - at least - need to secure a visa ahead of time and possibly a waiver of the criminal inadmissibility.
Contact the Australian embassy for details.
no
Australian female citizen marrying US male citizen - which would be easiest marrying in US and come back to Australia to live or marry in Australia to live?
Everybody. If you are a US citizen you can go without a passport. If you are not a US citizen you can enter with proper passport and with an US visa.
Marry In Aus.
yes
If it's a valid US passport or you are a dual-citizen most likely
Two options: 1.US citizen can go to India marry and then spouse can enter using a K-3 spouse's of US citizen visa. 2.Alien can enter US on a K-1 fiance visa and marry the US citizen within 90 of entry to get conditional status.
Australia, US
Yes! A nyone who is not an Australian citizen needs a valid visa to enter and spend time in Australia.
when does a us citizen need a passport to drive to Canada
Most definitely
Costa Rica is not a US territory. If you try to enter the US with a Costa Rican passport, expect to be treated as a Costa Rican citizen and not a US citizen (that is, you'll need a visa, etc.). If you're a US citizen, get a US passport