Ok without even buying the Revan expansion you can experience his return. They actually did a good job with it. So apparently Revan was captured by the emperor and placed within a machine that channeld Revan's force power to the Emperor. You will free Revan from this machine in a flashpoint. The Exile Jedi Ghost woman is from the books I don't think she's in any of the games at all. I thought she was an older version of Bastila but she's someone else entirely.
Are you onto something or just on something?