Short answers, pulled from the story.
The Norwegian Campaign was a military campaign fought from the 8th of April to the 10th of June 1940, in which Allied forces attempted to defend Norway against a German invasion. It ended with Germany occupying all of Norway, while King Haakon VII and the Norwegian government escaped to exile in London.
Germany invaded Norway primarily to secure the port of Narvik and the coastal waterways used to ship Swedish iron ore, which Germany depended on for steel production. Control of Norwegian ports and air bases also provided strategic advantages in the Battle of the Atlantic, allowing U-boats and aircraft to operate against Allied convoys.
There were two naval battles at Narvik. In the First Battle on the 10th of April 1940, Captain Bernard Warburton-Lee led five British destroyers into Narvik harbour, sinking two German destroyers and six supply ships but losing his own life and having several ships badly damaged. The Second Battle on the 13th of April saw the battleship Warspite and escorts destroy the remaining German destroyers, with the Germans scuttling their ships after running out of fuel and ammunition.
Vidkun Quisling was a former Norwegian defence minister and leader of the Nasjonal Samling party. His meetings with Hitler in December 1939 helped ignite Hitler's interest in occupying Norway. On the 9th of April 1940, he seized a radio station and declared himself Prime Minister, but his coup government lasted only until the 15th of April when the Supreme Court of Norway appointed an Administrative Council in its place.
The failure of the Allied central Norway campaign, including the costly withdrawals from Namsos and Åndalsnes in early May 1940, is considered a direct cause of the Norway Debate in the British Parliament. That debate resulted in the resignation of Prime Minister Neville Chamberlain and the appointment of Winston Churchill to the office.
King Haakon VII fled Oslo when the German invasion began and refused German demands to recognise the Quisling government. He and Crown Prince Olav escaped aerial attacks on Elverum and Nybergsund before eventually reaching Tromsø, which served as the de facto Norwegian capital from the 1st of May. He and his government then escaped to the United Kingdom before the campaign ended on the 10th of June 1940.