As to the leaders advantages propigating down, I'll quote the AACW's manual from the Wiki:
In addition to providing CP’s, as every leader does, the commanding officer of a stack (i.e. highest-ranked most senior leader present) improves the capabilities of his subordinate units with his offensive/defensive rating (+5% to combat for each point) and his special abilities. His strategic rating also has a critical impact on the stack’s performance (see below). Units in a division not only benefit from the benefits just described, but also from their own divisional leader’s capacities.