No direct flight to Dublin
The airlines that fly from New York to Luton Airport in London are American Airlines and United Airlines. These can be booked on Expedia.com.
6 hours
WestJet do.
American Export Airlines
yes
Unfortunatly I don't know.
Many airlines fly between London in England and Dublin in Ireland. You can book on their websites.
Domestic Airlines fly nationally (inside one country, such as New York City to Denver) and International Airlines fly internationally (from one country to a different one, often times overseas, such as New York City, USA to Frankfurt, Germany).
The flight time is 12-13 hours with LOT, Austrian Airlines, American Airlines, Bruxelles Airlines, Swissair etc.
Seems there is no such flights, at least to Miami. You can try to check at onetwotrip.com if you need to travel to another city, after you'll choose starting poin, destination and dates, in the search results there is "Direct Flights Only" option
No, American airlines only flies to New York, California and Kansas. You could take a plane to NY and drive there though...
New Zealand has their own airline, Air New Zealand that obviously fly to and from New Zealand. You can also fly with Qantas, Emirates Airlines, Singapore Airlines, China Eastern Airlines and United, who all have services that fly to New Zealand.