This is a very quick post to explain how I would expect various aspects of unit movement and facings to work inside the game as well as a units Zone of Control (ZC) in more detail.
The Brigade in the above unit is going to use a number of move actions in order for it to wheel towards the east.
To do so, the front left hand side of the unit is essentially pinned in place so that when the unit wheels that point on the unit always remains in the same place.
The right hand edge of the unit has had to move 6 cm to make this wheel happen, therefore the unit would have used 3 actions to make this wheel.
UNIT FIRING ARCS
Continuing with our example above the Brigade can now fire at any target within range inside its front 45 degree arc:
ZONE OF CONTROL
All units in the game have a Zone of Control (ZC) which extends from the units front arc for a distance of 10 cm.
Enemy units within this ZC have to react to this unit or the closest enemy unit. i.e. they must either move directly towards or directly away from the unit that is facing them. This is to represent a unit being unwilling to show its flank to the enemy and therefore moving in such a way so as to reduce this risk.
In the above example we can see that the Zone of Control of the Red unit extends outwards at a 45 degree angle from its front base edge and includes the Blue unit Brigade 1. Blue Brigade 1 will have to finish all movements facing towards the red unit and it can only move directly towards or directly away from the Red unit.
In this example, the red unit will also be in the blue units zone of control and so will also have to act in the same manner.