What is that on top of his hat? Feathers?
The hat is called a shako, and it is either adorned with an upright pom-pom or feathers. The pom is jokingly referred to as a donkey di-- by VMI cadets. The feathers on a shako are worn only by cadet officers who are all first classmen or seniors. The pom is worn by all other cadets, including first classmen who hold no rank (1st class privates).
In the photo above, Hardy wears the chevrons of what today is considered a Lt, but back then may have been an NCO (times change, as did rank structure). Back then, there were far fewer cadets and he appears to be an NCO as indicated by virtue of his short sash and his belt buckle (more later).
Rank at VMI and Citadel is indicated by the number of upright Chevrons only (you count the black portion of the chevron, not the gold outline - thus Hardy has 2 chevrons). The number of upright chevrons indicates whether you hold the rank of Corporal, Sgt, Lt or Captain.
Those are the only 4 ranks held at VMI. Five Chevrons is the Regimental Commander, the highest ranking cadet at VMI. Four chevrons are worn only by the Regimental XO and Battalion Commanders; 3 chevrons are worn by all Company Commanders and Regimental Staff Officers; 2 Chevrons are worn by all Battalion Staff Officers, Company XO's and platoon Lt's; 1 chevron is worn by all degrees of Sgt's; and one chevron on the lower sleeve cuff indicates a Corporal. The symbols/Chevrons beneath the rank chevrons, such as the horizontal stripes under Hardy's chevrons, indicate your position if you are a staff officer either in a Bn or Regt.
The current rank system at VMI is as follows: Rats hold no rank. Once out of the ratline, they still hold no rank, but lose the moniker "rat" and are then referred to as 4th classmen. 3rds, or sophomores, may hold the rank of private or Corporal only. Promotion to Corporal requires them to be involved in the rat training program. 2nd's, or juniors, are either privates or Sgt's of various rates - color Sgt's, platoon Sgts., Battalion and Regimental Sgt's, etc. Being a first class private at VMI in the 50's-90's used to be a unofficial "honor", with first class privates wearing the oval VMI brass belt buckle and bragging about their status as privates, especially if they were privates for all 4 years. Not so much today, as more opportunity for rank has popped up with the increase in class sizes and additon of women to the Corps.
Belts also indicate rank and seniority, with Officers wearing the square Officers Buckle; Sgts wearing the round centurion belt buckles; and VMI privates wearing the oval VMI brass buckle. All other cadets used to wear a standard enlisted brass buckle like found on boy scout uniforms, but have since moved to a square buckle with VMI emblazoned on it.
Swords and Sashes are for NCO's and Officers only, with the sash worn to the wearer's left; knee length for officers and mid-thigh for NCO's.