The fates of your original companions varies depending on what you ask him, what you tell him, and what order you ask him. Some people actually had Neeshka at their wedding at the end. A lot of characters can survive if you simply don't ask about them, it seems. Khelgar and Jerro are the only ones assured to live. I think Qara is doomed to die, though. I think an example of asking in order is Grobnar/Construct. If you ask about Grobnar first, he sings a song as he escapes. If you ask about Construct first, Grobnar tries to shield Construct and dies. I think that's because if you ask about Grobnar first, the game isn't certain you even had Construct.