I can say that Kreia is not bastila because as a writter you dont want to step on other company's characters. Odision will make thier own characters and only give cameos to kotor1 characters.
Ex. the mask of Nihilus was originally going to be made out of Revan's skull but the removed that idea since the players would be angry that you tossed away such an important and closely deared character to the players.
You will find that in TOR there is not a lot of detail on what happen to the Exile since Bioware wants to give room if lucas arts ever wanted to do a game between kotor2 and TOR. The game could be a rpg or even a game like jedi knight based in the old republic.
On topic Bastila went into hiding either before or after katarr.