Question about the 'Necromancy' skill and 'Necro Call'

[Jamers]

Thanks for reading.

So as I'm sure you all know, a bit was lost in the translation of this game to English and the descriptions of things are not always clear. I was wondering:

-Does the Necromancy skill work as it does in the HoMM games, where AFTER a battle, some troop of undead would receive a boost to their numbers? If so, how does the game determine WHICH troop gets pumped up? Is it like Heroes, where only skeletons are raised, or at the end of a battle the lowest LEVEL troop of undead receives a boost, or what?

-Also, regarding the spell Necro Call: is this basically just like a Resurrection for undead units, bringing back to life a certain number of the SAME unit that died, based on Intellect, Chaos Magic skill, etc., or does it just raise a number of random undead units from ANY dead troop--enemy or friendly? Also, does this troop remain with the army after battle if there is room, or is it just temporary like other summoning spells (Dryads' Summon Thorns, etc.)?

Thanks again...any input is much appreciated!