The amount of damage a unit can suffer before being eliminated is described in "hits" (hitpoints). These hits, together with the other unit parameters model the properties of the units. A cavalry unit will have for example other parameters than infantry. The parameters MenPerHit, HorsesPerHit (and GunsPerHit) do nothing but to translate the hitpoints in an actual number of men, horses (guns) to show it to the player on the unit interface. These numbers do not influence the battle mechanic however.
Should I add manually that column?
Yes.
Cheers
Norbert