Great write-up for the Sarkans (and Tholothians, but I'm more enticed by one of my requests being written), the justifications behind their characteristics makes for a really interesting brawny+stubborn, cultured-yet-antisocial race. Might be fun to play as a Doctor or Entrepreneur.
Only thing I'd debate is using hard numbers for Cold-Blooded (especially in Fahrenheit; these aren't the Imperial measurements you're looking for). I think it should be abstracted into 'freezing' and 'hazardously cold' temperatures and left to the GM to decide when the environmental situation falls into one category or another.