Bastila Shan's character was originally meant to be Vima Sunrider, a young heroine from Dark Horse Comics' "Tales of the Jedi" series who is instructed in the ways of the Jedi in the series "Redemption".
When you first see Mission in the Undercity of Taris she will ask you for help because her friend has been captured. If you refuse to help her Carth will say "Gadon said this girls the only one who can get us into the Bek base" but you need Mission's help to get you into the Black Vulkar base.
Ignus, the manager of the hotel in Manaan. He tells you that he saw Sunry running away from the hotel after he heard a blaster shot when you ask about the murder. If you use Force Persuade to get him to testify to the court that Sunry left after the shot he doesn't and it is harder to try and find Sunry innocent.
Yes, the canonical ending has Revan (as a male) rejoining the Jedi order, falling in love with Bastila, saving her from the dark side and defeating Malak.