Short answers, pulled from the story.
Apollo 10 was a "dress rehearsal" for the first Moon landing, designated an "F" mission by NASA. The crew tested all spacecraft components and procedures up to, but not including, powered descent and landing. The mission confirmed that Apollo 11's planned landing site in the Sea of Tranquility was suitable.
The Apollo 10 lunar module Snoopy came within 7.8 nautical miles of the lunar surface on its closest approach. Astronauts Thomas Stafford and Gene Cernan flew two low passes over the planned Apollo 11 landing site before rejoining John Young in the command module.
NASA deliberately prevented a landing by short-fueling the ascent stage of the lunar module. The ascent stage carried only about 2,631 lb of propellant, roughly half the amount needed to lift off from the surface and rendezvous with the command module. The lunar module was also an early, heavier design weighing 30,735 lb, compared to the 33,278 lb Apollo 11 module.
On the 26th of May 1969, the Apollo 10 crew reached a speed of 39,897 kilometers per hour (24,791 miles per hour) relative to Earth's surface during their return from the Moon. This remains the highest speed ever attained by a crewed vehicle relative to Earth.
The command module was called Charlie Brown and the lunar module was called Snoopy, names taken from Charles Schulz's Peanuts comic strip. Schulz approved the names with some hesitation. Snoopy had already been associated with NASA's safety recognition program, with outstanding workers awarded silver Snoopy pins.
After the mission, Snoopy's ascent stage was jettisoned into a heliocentric orbit and was not tracked after 1969. In June 2019, the Royal Astronomical Society announced that a small Earth-crossing asteroid designated 2018 AV2 is likely the spacecraft, with 98% certainty. Snoopy is the only once-crewed spacecraft believed to still be in outer space without a crew.