Dante wrote:
All Death Mongers must start with one preferred role of the three: the Father (Neroth), the Mother (Beltine), or the Offspring (Sarish). Initially, all deity-based choices, such as spells, weapons, armor, and skill advancement (for the Divine archetype) are based upon that deity; and their first stage in the Death Monger Priest path must choose the talent corresponding to that initially chosen deity. The character's role-choices in the second and third stages in the Death Monger Priest path each determine not only the path's granted talent but also open the options of spells and skill advancement for that deity; however, weapon and armor talents are not automatically granted by that path and must be taken separately.
Death Monger armor and weapons are different from any of the three deities. From what I remember, armor = any chain and weapon = short spear.
As to the rest, I think Cody's ruling is much closer to the intent implied by Henry's answer about deity skill (you can choose any of the three).