Short answers, pulled from the story.
Capcom released Elena as a new character in 1997 with the launch of Street Fighter III: New Generation. Akira Yasuda and Hiromi Kotobuki created her to be the first fighter from Africa in the series.
The development team chose Capoeira as her fighting style because it involves dance and movement. Artist Kinu Nishimura drew her emphasizing her behind when Capcom requested sexier designs for the game.
Elena stands 183 cm tall with measurements of 83-58-88 cm according to official game data. Her original outfit featured a white foldover bikini bottom and cloth strips crossing over her breasts.
Saki Fujita and Karen Dyer provided Japanese and English voices respectively for later appearances after Kaoru Fujino originally voiced Elena before Mie Midori took over duties with 3rd Strike release.
Elena appears in the first volume of Street Fighter III: Ryu Final manga by Masahiko Nakahira and UDON Entertainment included her in Street Fighter Legends: Ibuki as a new student meeting Makoto and Ibuki.