Short answers, pulled from the story.
James Allen was New Zealand's first foreign minister, appointed on the 24th of November 1919 by Prime Minister William Massey to the post of Minister of External Affairs. Before that appointment, New Zealand had no dedicated ministerial portfolio for foreign relations.
The title "External Affairs" was used in deference to the British Government's role in conducting foreign policy on behalf of the British Empire and later the Commonwealth of Nations. Calling it "Foreign Affairs" would have implied that Britain was a foreign country. The title changed to Minister of Foreign Affairs in 1970 when the department was renamed.
Keith Holyoake was the longest-serving New Zealand foreign minister, holding the post from the 12th of December 1960 to the 8th of December 1972, the full duration of his eleven-year prime ministership. Don McKinnon was the longest-serving foreign minister who was not also prime minister.
Thirteen New Zealand prime ministers have held the foreign affairs portfolio, including Peter Fraser, Walter Nash, Keith Holyoake, David Lange, and Mike Moore.
In 2005, responsibility for trade was removed from the foreign affairs portfolio and returned to a separate portfolio, restoring the title to Minister of Foreign Affairs. The trade portfolio had been merged in 1993 to create the title Minister of Foreign Affairs and Trade.
Don McKinnon became Commonwealth Secretary-General after leaving the role of foreign minister, which he had held from 1990 to 1999 under prime ministers Jim Bolger and Jenny Shipley.