If you are a US citizen, you will need both a valid US passport and an Australian ETA visa to travel to Australia.
If you are form Australia than no need to passport to travel < a href=http://www.cruiseeasy.com.au/>cruise Australia.
No!
Yes
No of course not. You don't need a passport to travel within one federal country!
No, but you do need a valid passport.
When traveling from Puerto Rico to Florida, no passport is needed. Puerto Rico is part of the US, as is Florida. Traveling from Puerto Rico to Florida is travel within the United States. Citizens do not need a passport to travel within the US, although they do need some form of government-issued photo identification to get on a commercial airplane and a passport will serve that function. Non-citizens who are in Puerto Rico have already entered the US using a passport (or similar document for Canadians) and so need only the identification they would need to travel within the US, for example, from Miami to Atlanta, to travel to Florida or other locations in the US.
You'll need a US PASSPORT to return to the US.
Yes, anytime you leave the country you do.
Key West is a city in Florida. Provided you are a U.S. citizen, you do not need a passport.
No, they would not.
No. The travel is within the same country and does not cross international borders.
You do not need a passport to travel from Wisconsin to Florida. If you are flying, you need government-issued photo ID, but a state drivers license or state ID card will work just fine.