Since you removed undead -lds from glory, at least leave it in necromancy skill.
I know about zerock`s abilities, but have no idea how to use their scripts in giving bonus to kids
Soul drain i thought like description of necro call spell : it rises certain amount hp, but no more units then killed stack. So soul drain gives ghosts something like 30-40% of dealt dmg, but no more then number of killed units. As you said lower of those two.