Short answers, pulled from the story.
Paul Tutmarc of Seattle, Washington invented the first electric bass guitar in its modern form during the 1930s. His company Audiovox featured the "Model 736 Bass Fiddle" in its 1935 sales catalog, and around 100 were made.
The Fender Electric Instrument Manufacturing Company began producing the Precision Bass in October 1951. Leo Fender and George Fullerton developed it as the first mass-produced electric bass guitar.
Monk Montgomery was the first bassist to tour with the Fender bass, playing in Lionel Hampton's postwar big band in 1953. He may also have been the first to record with the electric bass, at a session on the 2nd of July, 1953, with the Art Farmer Septet.
The Hofner 500/1 became known as the "Beatle bass" because of its use by Paul McCartney. It was constructed using violin techniques by Walter Höfner, a second-generation violin luthier, and first appeared at the German trade fair Musikmesse Frankfurt in 1956.
The Music Man StingRay, introduced in 1974, was the first widely produced bass with active powered electronics built into the instrument. It was developed by Music Man Instruments, founded by Tom Walker, Forrest White, and Leo Fender.
Roundwound strings have a winding wire with a circular cross-section wrapped around the core, while flatwound strings use a rounded-square cross-section winding. The choice between them has considerable impact on the instrument's sound and is often tied to specific musical genres.