He weared white/orange as rebe...erm...Republicans do, he don't goes for fashion :D
He used the clothes he had on when he joined Revan and turned against the republic.
He-s a clone (a good clone) of Vader for KOTOR, as he turned against the jedi, (against anyone including his master)...he was even better than Vader as DS-er : he tried to eliminate his master out of hatred and power, not as Vader couse of Luke...yep, he could have become a great Sith Master...but only if he would had 5-15 extra years for evolving