A Weapon Team must be deployed at the same time and within 3" of the unit it was bought with (also known as its parent unit). After this the Weapon Team is free to move and counts as a normal unit for all purposes (victory points, etc.). When within 3" of its parent unit, a Weapon Team can use that unit's rank bonus to modify its own Leadership. A Weapon Team within 3" of its parent unit is treated in all regards as having a 4+ ward save against ranged attacks such as missile fire and spells. This represents the team lurking in obscurity, and ducking for the protective cover of the larger unit.
A destroyed, fleeing or broken Weapon Team never causes Panic tests in friendly units.