I also have a question regarding the necronomicon. Should a melee character who barely uses magic ever bother aiming towards necromutation? Like late game, your armor skill is maxed out, throw on necromancy for a while and turn into undead?
I'd only REALLY recommend it if you're Demonspawn, honestly. TSO provides decent torment protection and healing and whatnot on kill and is usually my preferred way of dealing with extended. For Demonspawn though, Necromancy is their best aptitude AND they can't worship good gods. That said, if you have to choose ONE magic school to branch into and you don't want to worship a good god[Zin is also pretty great, for the record], Necromancy is your best bet. Ironically, full casters probably get LESS use out of the Necronomicon since the high-level Necromancy spells[Death's Door, Necromutation & Bornjor's Revivification] work best in a set and that's 23 spell levels you need to dedicate right there. Melee characters easily have that many and don't have as many dedicated to high-level offense spells, so they can afford the investment better.
I've never gotten far in the dungeon as a mage, but I can tell that there can be a case where they can run out of food by repeatedly casting high level spells. My problem is that the dangers of starvation has been reduced to just that, mass casting of high level spells. I really liked it when I could breath a sigh of relief at not having to worry about food after picking ghoul.
I guess that's fair enough. No spell hunger is still pretty powerful though, especially combined with channeling. Not that I've ever gotten a Mummy far enough that it becomes relevant, though. Stupid -2 aptitudes in everything...