Short answers, pulled from the story.
Major Malcolm Wheeler-Nicholson founded National Allied Publications in 1935 at 432 Fourth Avenue in Manhattan. The company's debut publication was New Fun: The Big Comic Magazine #1 with a February 1935 cover date.
Jerry Siegel and Joe Shuster created Doctor Occult as the earliest recurring superhero created by DC that is still being used. This character appeared in issue No.6 of New Fun Comics in December 1935.
Detective Comics No.27 introduced Batman in March 1939 through Bob Kane and Bill Finger. The masked vigilante wore a caped suit known as the Batsuit and drove a car later referred to as the Batmobile.
Editor Julius Schwartz directed Irwin Donenfeld and publisher Jack S. Liebowitz to produce a one-shot Flash story in Showcase #4 during October 1956. Schwartz and Carmine Infantino then revitalized Batman in what the company promoted as the New Look with relatively down-to-earth stories emphasizing Batman as detective.
The company officially changed its name to DC Comics in 1977 after using Superman-DC since the 1950s. In March 1989, Warner Communications merged with Time Inc., making DC Comics a subsidiary of Time Warner.