Short answers, pulled from the story.
The Gran Sasso raid took place on the 12th of September 1943 and was a German military operation to free Benito Mussolini from imprisonment at the Hotel Campo Imperatore on the Gran Sasso d'Italia massif. The operation was codenamed Operation Oak by the German military and was personally ordered by Adolf Hitler.
Major Harald Mors planned and commanded the entire Gran Sasso operation, including the ground assault. General Kurt Student oversaw the mission at Hitler's direction, and Oberleutnant Georg Freiherr von Berlepsch led the airborne element. SS officer Otto Skorzeny joined the raid uninvited and later received most of the public credit despite playing a lesser planning role.
SS-Obersturmbannführer Herbert Kappler discovered Mussolini's transfer from La Maddalena through a letter written by Edda Ciano. Kappler's agents, paid with counterfeit money from Operation Bernhard, intercepted security messages pointing to Gran Sasso. A German doctor then posed as a prospective clinic operator at the Hotel Campo Imperatore to confirm Mussolini was held there.
No. By the day of the raid, Germany already controlled the territory surrounding the Hotel Campo Imperatore, making the rescue far less dangerous than advertised. Nazi propagandists marketed Operation Oak as a stunning military feat to boost morale, but the Carabinieri guards showed little willingness to fire on German troops, and the operation lasted only minutes.
Skorzeny was promoted to Sturmbannführer, awarded the Knight's Cross of the Iron Cross, and publicly dubbed the most dangerous man in Europe. His autobiographies, Geheimkommando Skorzeny published in 1950 and Meine Kommandounternehmen published in 1976, kept his version of events dominant for decades, despite the objections of the paratroopers who actually planned the mission.
After leaving Italy, Mussolini travelled to Vienna, Munich, and then East Prussia, where he reunited with Hitler on the 14th of September 1943. Hitler compelled him to return to Italy to lead the Italian Social Republic, a German-controlled puppet state in the north. Mussolini and his mistress Clara Petacci were captured by Italian communist partisans and executed near Lake Como on the 28th of April 1945.