Short answers, pulled from the story.
The Golden Age of Television is generally recognized as beginning in 1947 with the first episode of Kraft Television Theatre and ending in 1960 with the final episode of Playhouse 90. Some historians use slightly different boundaries; producer David Susskind defined it as 1938 to 1954, while The Television Industry: A Historical Dictionary places it from the 7th of May 1947 to 1957.
The Golden Age was defined by a large number of live productions broadcast directly to viewers, with no second takes and sets that had to be changed during commercials. It was also marked by highbrow programming including original teleplays, classical music performances, and the first television appearances of figures such as Leonard Bernstein and Arturo Toscanini.
Several events converged to end the era: the quiz show scandals of 1958, a writers' strike in March 1960, the final broadcast of Playhouse 90 in May 1960, and the departure of director John Frankenheimer. Network executives also shifted programming toward rural sitcoms and Westerns that drew larger audiences than highbrow productions.
Gorgeous George Wagner made his first television appearance on the 11th of November 1947 and quickly became a national celebrity. His theatrical character drew large audiences to professional wrestling broadcasts and, according to sources at the time, was probably responsible for selling as many television sets as Milton Berle.
The first practical videotape system was Ampex's Quadruplex, which became available in 1957. Before that, all television was either live or filmed. Even after videotape arrived, editing it required a razor blade, so retakes remained rare and shows were often still shot live to tape.
Reginald Rose's Twelve Angry Men and Paddy Chayefsky's Marty were both adapted from Golden Age teleplays and went on to wide acclaim as films. The first screen adaptation of a James Bond story was also a 1954 teleplay, a production of "Casino Royale", broadcast years before the film series began.