This is from some A.M.I. notes I took and either came from "Tulip in her Glory", Vol. 17, Page 68 of the Arkansas Historical Quarterly (Spring, 1958) or "Historic Tulip, Arkansas" by Jonathan K.T. Smith written in 1989.

"For their classes the students had a good school plant and pleasant surroundings. The school buildings were located in Tulip-proper, on the flat, rolling land there. The buildings, though not elaborate, were well built and the drill ground provided an excellent place for the public meetings and regular drill activities. The two schools were served by a wonderful library, full of choice items (3). It is intimated that a huge geological collection was placed at the disposal of the schools. In 1852 the General Assembly of Arkansas made a provision that the first geological survey of the state be taken.
The cadets felt very important in their uniforms; they were exactly like those worn at West Point, except for the buttons. All of the cadets were over fifteen or at the least fourteen, and could not exceed four feet, nine inches in height at admittance. The older cadets lived in barracks on the ground while the younger boys and girls boarded in homes adjacent to the school."

Assuming this is factual it would mean that A.M.I. was a prepatory school and not a four year college such as the Virginia Military Institute or the Georgia Military Institute. Fourteen and Fifteen year-olds were not college material even back in the 1850's.

It would seem that once the school year was over the cadets would return home for the summer. Wouldn't the census takers report them as residents at their permanent adresses and not as temporary residents of Tulip? Also wouldn't those cadets who were old enough to enlist when the War broke out, enlist in hometown units with their family and friends?

The cadet guns and twelve pound howitzer probably were turned in at the Arsenal but not until 1861 when it was under Confederate control. Refer to the ad below.

LITTLE ROCK] ARKANSAS TRUE DEMOCRAT, August 29, 1861, p. 2, c. 7
Arms Wanted.
The undersigned, having been appointed Agent by the Confederate States for the purchase of Arms, is desirous of purchasing all the good Guns in the country.
He will not only purchase "regulation arms," such as Muskets and Rifles, both Flint and Percussion made for the army, but also Double Barrelled Shot Guns and Country Rifles, Percussion Locks.
Every man who has a Gun of the above description, can sell it for Cash by making application to the undersigned.
Apply at the Arsenal. John A. Jordan,
Little Rock, Aug. 29, 1861

This is speculation on my part but it does make sense.