Short answers, pulled from the story.
Stephen A. Saliga named the Pioneer program after serving as chief designer for Air Force exhibits at Wright-Patterson Air Force Base during the late 1950s. He chose this name because the Army Public Information Office had already identified the Army as Pioneers in Space.
The first launch attempt occurred on the 17th of August 1958 under the designation Pioneer 0. This Thor-Able rocket failed just 77 seconds after liftoff and destroyed the payload.
Pioneer 6, Pioneer 7, Pioneer 8, and Pioneer 9 formed a distributed monitoring system across the inner Solar System. These four spacecraft entered solar orbits to sense parts of the Sun several days before its rotation revealed them to Earth orbiting instruments.
March 1972 marked the launch of Pioneer 10 toward Jupiter and beyond. Both Pioneer 10 and Pioneer 11 became the first artificial objects to achieve escape velocity leaving the Solar System entirely.
The Pioneer Venus Multiprobe known as Pioneer 13 included multiple atmospheric impactors designed to study different layers of the atmosphere. Three smaller impactor probes each weighed 75 kg including North Night and Day variants while the Pioneer Venus Large Probe weighed 300 kg.