Do the races actually mean something or is that just just cosmetic? If I put a Klingon as my tac officer does my ship do more damageor something?

Right now, the only race that make's a difference is Saurian, as some Uncommon Saurian BOs (but not all) have the Space Skill 'Efficient'. (And may the buyer beware in the Exchange... There are a lot of over-priced Uncommon Saurian BOs listed that DO NOT HAVE THIS TRAIT, and are posted in the hope that someone buys them out of ignormance...)