I wouldn't want Dantooine or Korriban in KotOR III in actual gameplay unless their maps were drastically increased, because that was disappointing to me in KotOR II, esspecially Korriban. If any Dark Side planet should be visited, it should be a completely new one or Yavin IV, and for planets with Jedi Temples, probably Coruscant since I can't think of any other ones.
As for the character being an illegitimate child or either Revan or the Exile, I would have to say he/she would be the Exile's son/daughter. He had far more chances to get frisky with certain crewmates than Revan ever did.
