RE: Single unit firing vs multi-unit firing
IIRC the amount of casualties you inflict has an influence on the morale check of the enemy. So it's a tradeoff, do you use more than one unit to increase the chance of Disruption or do you save the other units for a future assault if the one unit firing is enough for disruption.
"Tapfer. Standhaft. Treu." - PzGrenB.13 Ried/Innkreis