This summary is based on the men who served in Field and Staff or company A or E. I will add the other men as I add the information from the descriptive books.
When they enlisted, men's hair color, eye color, complexion, and height were recorded. In theory, this helped identify soldiers. Assuming everyone used the same terminology, and distinguished the colors in the same way, it would at least reduce the number of possibilities. I don't know whether there was a standard list of colors, or how some of the colors were distinguished, but given the variations, I doubt descriptions were consistently recorded by different examiners.
The shortest men were Franklin B Miller (co.A, F&S) and Frank Miller (A). (Are they the same person? The Company A descriptive book has two entries!) According to paragraph 929 of the Revised army regulations of 1861, enlistees had to be at least five feet three inches high. This rule, however, was waived for musicians and for people who were reenlisting.
The tallest man was James Gere, at 6 feet 3-1/4 inches. On average, they were about 5 foot 6 inches tall (mean 66.7", median 66.5", mode 66.0").
Most men had either a dark or light complexion. But others were described as having fair, ruddy, florid, brown, sallow, or sandy complexions.
Eye colors were similarly uniform. Most men had either blue or grey eyes. Others had brown, dark, hazel, light, or black eyes.
The two most common hair colors again accounted for more than half of the men. Most men had dark or light hair. Others had brown, dark brown, grey, black, auburn, red, sandy, or fair hair.
The most common combination, accounting for about fifteen percent of the men, was blue eyes, light hair, and a light complexion.
QUESTIONS: Was there a standard list of colors? How were "light" and "fair" complexions (e.g.) distinguished?