Short answers, pulled from the story.
Street Fighter III: 2nd Impact introduced Hugo and Urien. Hugo is a professional wrestler from Germany managed by Poison, based on the Final Fight enemy Andore, who was modeled after Andre the Giant. Urien is Gill's younger brother, capable of manipulating electricity and metal.
Street Fighter III: 2nd Impact was released in October 1997 for arcades. It was developed and published by Capcom and ran on the CP System III hardware.
EX Specials are slightly more powerful versions of regular special moves. Players execute them by spending part of the Super Art gauge and pressing two attack buttons of the same type simultaneously while inputting the special move command.
2nd Impact was released as part of Street Fighter III: Double Impact for the Dreamcast in 1999, alongside the original New Generation. It was also included in the Street Fighter 30th Anniversary Collection released in May 2018 for PlayStation 4, Xbox One, Nintendo Switch, and Steam.
Parry the Ball is a minigame that appears after the player defeats three CPU opponents in single-player mode. The character Sean throws basketballs at the player, who must practice parrying them. Bonus rounds had last appeared in the series in Super Street Fighter II before 2nd Impact brought them back.
Yuki Iwai worked on the soundtracks for both Street Fighter III: New Generation and 2nd Impact, while Hideki Okugawa contributed to all three Street Fighter III games. The music is predominantly drum and bass, with jazz, hip-hop, and techno elements.