Short answers, pulled from the story.
Super Street Fighter II introduced four new fighters: Cammy, a 19-year-old special forces agent from England with a past tied to M. Bison; T. Hawk, a Native American warrior from Mexico whose ancestral homeland was seized by Shadaloo; Dee Jay, a kickboxing musician from Jamaica; and Fei Long, a Hong Kong movie star modeled after actor Bruce Lee.
Super Street Fighter II was released in arcades in 1993. The Super NES and Sega Genesis home versions arrived in June 1994 in Japan, North America, and Europe.
Super Street Fighter II was the first game in the Street Fighter series to run on Capcom's CP System II arcade hardware. The CP System II supported more sophisticated graphics and audio than the original CP System used in earlier Street Fighter II versions.
Super Street Fighter II: The Tournament Battle is an alternate version supporting eight-player single-elimination tournaments across four networked arcade cabinets. Play is divided into three stages: initial eliminations, semifinals, and finals, with players reassigned to different cabinets after each round based on their results.
Super Street Fighter II sold two million copies worldwide across its home versions. In Japan, the Super Famicom version sold 941,000 copies in 1994 alone, making it the third best-selling game in the country that year.
Reviews were mixed. Electronic Gaming Monthly's four reviewers agreed the additions were limited given how many prior versions had been released, and argued Capcom should have made a Street Fighter III with new mechanics instead. GamePro described the new features as "pretty cosmetic or just downright boring and unimportant" but concluded that "Street Fighter is still the best fighting game ever made."