Fire teams in the rifle platoon evolved with weaponry. During the period when I was enrolled in Advanced Infantry Training, it consisted of a riflemen (M-14), an automatic rifleman (Browning Automatic Rifle) and a grenadier (M-79 grenade launcher). As assault rifles with full automatic firing capability replaced semi-automatic infantry rifles, the dedicated automatic rifle became superfluous. Regardless of their weaponry, the fire team is the most basic infantry unit. It may function autonomously or as a part of infantry squads, platoons, and companies.
Ideally, a fire team is led by a fourth member, a sergeant (three stripes, E5). However, during the troop buildup in Vietnam, there were an insufficient number of non-commissioned officers (sergeants) of all grades, and a fire team might be led by a specialist/corporal, or even a private first class. Thus, in most cases, the team leader how no more training or experience than the men who followed him. Interestingly, the Fidelistas didn't have anyone with any experience in combat except for Fidel and Raúl who had fought poorly in the attack on the barracks at Moncada that led to their arrest, imprisonment, and exile to Mexico. Not an auspicious recommendation.
I'm sure that the Fidelistas had to learn basic team concepts such as fields of fire and fire and maneuver techniques just as we did in Advanced Infantry Training. Thus, I used those descriptions in Rebels on the Mountain.
I had to get creative in Rebels on the Mountain, imagining how the Fidelistas could have passed this training on to the recruits that joined them in Cuba. American Army training centers have well designed and constructed facilities to provide venues for recruits to learn and practice combat skills. The Fidelistas would have had to construct field expedients of their own design. It was fun imagining how I would have accomplished it.