Short answers, pulled from the story.
The island was named by Pedro de Ortega Valencia, a member of the 1568 Spanish expedition led by Álvaro de Mendaña de Neira, after his hometown of Guadalcanal in Andalusia, Spain. Britain formally confirmed the spelling in 1932 to match the original Spanish town name.
Archaeological finds at Poha Cave and Vatuluma Posovi show habitation on Guadalcanal since at least 4500-2500 BC. The Austronesian Lapita peoples arrived later, migrating to the island between approximately 1200 and 800 BC.
The Guadalcanal campaign, fought from August 1942 to February 1943, stopped Japan's southward expansion in the Pacific. The multi-day Naval Battle of Guadalcanal in early November 1942 forced a Japanese withdrawal and resulted in the sinking of the IJN battleship Kirishima, and is regarded by some Japanese analysts as equally significant as the Battle of Midway.
Henderson Field was the airfield at Lunga Point on Guadalcanal's north coast, seized by the 1st Marine Division on the 7th of August 1942 and completed by U.S. Navy Seabees. It was named after Major Lofton Henderson, a Marine aviator killed at the Battle of Midway. It is now the international airport for the Solomon Islands, located about five miles east of Honiara.
Douglas Albert Munro, a Signalman 1st Class in the U.S. Coast Guard, provided covering fire and helped evacuate 500 besieged Marines from a beach at Point Cruz on the 27th of September 1942. He was killed during the evacuation and was posthumously awarded the Medal of Honor, remaining the only U.S. Coast Guardsman to receive that honor.
The Guadalcanal Watersheds is a 376,146-hectare site covering roughly 70 percent of the island, identified by BirdLife International as an important bird area. It holds the greatest contiguous area of cloud forest in the Solomon Islands and supports threatened or endemic species including Guadalcanal moustached kingfishers, Woodford's rails, and Guadalcanal thrushes.