Well, first off, thanks for both the attention and the compliments!
I do have answers for most of them, and I think they're good answers, but I may be being subconsciously affected by my desire to not put in more work.
Lichform is in fact pointless for them. This is a great shame shared by all undead necromancers. I might have not given them that category, but blurred mortality is specifically a talent you see vampire NPCs using, and I wanted to keep that. I'd be nice if an alternative top talent for Necrosis could be made for natural undead, but I'm not sure how you could code that.
@This is probably doable.
Most likely, I should just make all of their racial talents non-unlearnable to prevent this.
Mockery of Life is taking it's cues from a canon talent; the Wyrmic's Swallow, which also deals weapon damage (and more of it, too.) The damage nerf was why I ended up making Mockery instant, iirc, as it was often underwhelming when used as an entire turn, especially on the spell-based characters the race implies. It was also probably a desire to make it more /different/ from swallow, and losing damage in order to do it faster seemed cool. Probably it should be half a turn instead of no time? not sure.
Basing the damage on level would make it easier to balance, but much, much, much, much, much worse. Perhaps more importantly, there aren't any damage scalings that work that way that I can borrow, iirc.
The standard for racials is 1/8/16/24, but the standard for UNDEAD racials is 1/4/8/12.
I'm v used to Necromancy+ giving Will O The Wisp an on-spell wisp summon effect, so I may not have considered that as an issue. The same addon moves Undeath Link away to necrotic minions, so I may have the same excuse there. Honestly, I so rarely go for minions and so often build adventurers that I'm v used to taking a couple of dummy talents to get at the stuff I'm actually after.
There's also, as an excuse that may actually be accurate, the fact that those categories are the ones that match onto the talents. The first talent is just about being undead, so it gives blurred mortality, the third is about being cold, so grave, and only on the fourth are you /controlling/ death.
Honestly, the ability to play a necromancer while being in a different class is one of my favourite things about the race. I'm pretty loathe to change it.
PS: Yes, but racial (including undead) categories are /always/ just named with the race's name.
