Finally, each game has a booklet with game-specific rules, setups, and historical notes.
Units are typically regiments or brigades, and some battalions.
Higher level HQ capacity determines how many CP's you can spend via one corps per turn. A division can be activated twice, but will suffer fatigue each time. The tactical possibilities are similar, except they are not the product of a rigid turn sequence, instead you use the divisions the way you want. Barrage, then blast a hole with some assaulting divisions, then move the exploiters through with a move or advance mission. Basically, you are looking at these things in somewhat more detail due to the shorter timescale.