What is a squad?
A squad is a tactical unit of up to 10 players that you gather temporarily together in order to get the necessary skill sets in your attack group (e.g., sniper, heavy armor, dropship pilot, hacker, etc.). Squads can be created and disbanded at any time. They can be considered the equivalent of RPG groups.
CF2.2 Heavy Weapons, p. 1-2 Crossfire is a bit loose with the term “squad”. Sometimes “squad” means a Rifle Squad or SMG Squad specifically, but sometimes it can mean any stand. The rules say “the term Squad will be used to describe game procedure that apply equally to both Squad and Heavy Weapons stands” (p. 2), but in fact the rules seem to use the term for any stand, i.e. Rifle Squad, SMG Squad, HMG, PC, CC, BC, FO, gun, mortar, or tank. This can be a little confusing, but if you keep these two possible meanings in mind when reading the rules, you can usually figure out what is intended in each section.