Short answers, pulled from the story.
Launch Complex 39 is a rocket launch site on Merritt Island, Florida, originally built as the Apollo program's Moonport. It has supported the Apollo program, the Space Shuttle program, commercial launches by SpaceX, and now NASA's Artemis missions targeting the Moon.
SpaceX signed a 20-year lease for Launch Complex 39A on the 14th of April, 2014. The first SpaceX launch from the pad was CRS-10 on the 19th of February, 2017.
The complex was designed to accommodate two competing approaches to reaching the Moon: direct ascent using a massive Nova-class rocket, and Earth orbit rendezvous using multiple smaller Saturn rockets. Early plans from 1961 included separate sets of pads for each approach. Once lunar orbit rendezvous and the Saturn V were selected, the Nova pads were dropped from the design.
The fully assembled Saturn V, mounted on its Mobile Launcher, was carried by crawler-transporter at a speed of 1 mile per hour over a distance of 3-4 miles to the pad. Each crawler weighed 2,720 metric tons and was built to keep the stack level while negotiating a 5-percent grade at the pad.
Blue Origin filed a protest with the U.S. General Accounting Office, claiming NASA planned to award an exclusive lease to SpaceX. On the 12th of December, 2013, the GAO denied the protest, ruling that the solicitation had expressed no preference for single versus multi-use arrangements.
Artemis I launched from Launch Complex 39B on the 16th of November, 2022, at 06:47:44 UTC, marking the first launch of NASA's Space Launch System rocket.