yes the only playables for this edition are those in the roster given in the first post. No the brotherhood characters are only replaced in the editions herostat (called heroreal here, so it doesn't overwrite the games natural herostat.engb), their files are not replaced, so they are still playable in the regular version.
everything in this edition is separate from the regular game, so you can launch the game with the game.exe and play the game as it comes or with whatever mods you want. this edition is launched by the new XMenBundle.exe, and runs files that are unique to it and not overwriting other important files.