New Zealand 
Entry/ Departure/ Safety
US Citizens travelling to New Zealand are eligible for a vsa waiver for stays up to 90 days in any given year.  You will need a US passport valid for at least 6 months from arrival, and a departure ticket either scheduled or open valid within the 90 days waiver period.   You may be asked to prove sufficient funds  ($1000NZ/ month without paid accommodations) or  ($400NZ/ month if accommodatiuons are pre-paid) ).  This can include cash, travelers checks, or credit/debit cards with sufficeint credit. 
For the most current information and details regarding policies ad procedures, please visit the Embassy of New Zealand's website.
Health:
No specific immunizations are required for travelers entering Australia from the United States, but always consult your physician or health practitioner about recommended procedures or immunizations, before traveling to foreign countries.
Saftey:
Crime rates in New Zealand are quite low and have been decreasing. The most prevalent crime is theft or attempted theft from cars, camper vans, and hostels. To help protect against theft, do not leave passports or other valuable items in unattended vehicles. Violent crime against tourists is very rare, but always use common sense and caution, particulary when traveling alone.