Thank you YankeeDog.
#1 and #2, understood. (I used the 20 and 37 cannon in fire support role, and my panthers as taxi's for my grenadiers for the first move or two, in the original games, both pretty useful!)
#3, In the panzer grenadier infantry company, 81's have an ammo truck with an additional supply of 81 ammo. However, In the heavy weapons company, the 75mm infantry guns have a truck, but with no further ammo?