1. Artillery Officer:
Smoke Barrage is very useful to charge in a heavy covered VP or other sector.
The enemy can't see what's coming, therefore can't suppress your infantry that quick or can't shoot AT at your tanks from far away. This is not used much but is so damn effective..
The mortar can also do this when you want to charge in a heavily defended area, or want to cap a VP without getting pinned.
Also, the second ability of concentrate fire is very useful. Try activating it when charging in, you'll notice the difference hard
2. Heavy Strafing Run (AT): Extremely effective against a big blob of infantry. Stops the attack because the units are pinned for what, 60 sec? (correct me if i'm wrong)
3. Hull down: See replies above
4. Command tank: I don't use it much.. can't give anything on that. I think it's a pretty weak unit.
5. Relief infantry: 1 ost squad / 6 units dead, but don't use it much.
6. Trenches: Great to lock down a certain area BUT doctrinal. Should be non doctrinal I think..
7. Arty: Very useful when the enemy is bunkered up
8. Smoke Bombs: See above about the smoke, but It takes a while to drop the bombs. It can cover a retreat though.
9. The grens in the SdKfz from Mech Supp: Just some grens in a sdkfz with LMG, nothing bad about it, not hing great.
I use the SdKfz to transport units from the HQ to the battlefield, I can't find no other use for it because it is extremely vulnerable.
Cheers