I agree with most of these replies. I too have a problem with my stupid hull mounted arty turning every which way until finally taking a round to their already pitiful side armor and blowing up. Except mine do it with little or no reasoning, even though they cant see the unit (but others can) they will constantly turn towards it exposing their vital sides to others that ARE in sight. Horrrrrrrific AI.
However, as one stated above, I also find it most effective to turn a tank towards an enemy, apply the "dont move" order and than engage them. This usually keeps them pointed at the right enemy. The downside to this is I find myself constantly pausing and unpausing the game to try and reconfigure my tanks just right everytime an enemy gets knocked out. In the later missions this can become frustrating considering the amount of enemies that usually find themselves appearing all over the map and usually turns a 30 minute scenario into hours of micromanaging.
Oh yeah, why dont we get the option to take control of individual tanks and troops? This could be done easily enough, even with a simple A W S D configurment.