Short answers, pulled from the story.
Japanese troops landed close to Gona in the early evening of the 21st of July 1942. This landing initiated the ground advance that led to the subsequent battles along the Kokoda Track.
Operation Mo was an attempt by Japan to capture Port Moresby through amphibious assault. The operation failed after being thwarted by the Battle of the Coral Sea in May 1942.
It took five days for fifty men to manhandle a single artillery gun forward through the dense jungle and mountainous terrain. This difficult movement occurred as part of the defense efforts against the Japanese advance on Imita Ridge.
Owen served as the commanding officer of the 39th Battalion until he was mortally wounded during the fighting. Major Allan Cameron then assumed command of the force after Owen's death.
Japanese forces holding Buna and Gona held out until the 22nd of January 1943. This resistance ended following a joint Australian United States operation that crossed the Kumusi River by the 16th of November 1942.