egdcltd has pretty much got it right. Terry, who was also one of the original RM designers, typically generates NPC stats by making them up off the cuff rather than going through the character generation process.....at least for the more powerful NPCs such as Gods, Loremasters, Navigators, etc. I have personally never had an issue with this. These types of powerful NPC's aren't typically direct adversaries and so their stats aren't all that important. The less powerful NPCs, of the type characters would have more serious interactions with, are more standardized.
Regarding the multiple professions, this is typically used to represent the NPC's base lists rather than indicating any real "multi-classing". So if an NPC is listed as a Magician/Illusionist, they aren't really two different classes but instead they have base lists from both Magician and Illusionist. Their actually development point costs would have come from either Magician or Illusionist.
This isn't much different than how I run my own campaigns. I tend to be quite flexible in character creation and if the player has a solid character concept I let them mix base lists from multiple classes for their base lists, but choose only one Profession for all intensive purposes.