What are you talking about? The tooltip text contains no errors. Sure, a couple things could be better worded for new players, but nothing is actually incorrect.

"1. Your HP is never reduced to 0 while under the effect of Living Dead."
No, it is. You just never get to see it because as soon as the server sees that the DRK will hit 0, it replaces Living Dead with Walking Dead, which gives the DRK a minimum HP value of 1. So a DRK pops LD, takes an attack that would reduce their HP to 0 or lower and in that instant, gets WD and has their HP set to 1.

"2. Some attacks just kill you outright, like enrages. The text should read "most attacks"."
Yes, because any attack that hits a DRK with Living Dead and would kill them gives them Walking Dead and that's the buff you quoted as saying "most attacks will not lower your HP below 1."

"3. The goal is not to reach 100% HP (i.e. this is not a "White Hole" mechanic). The goal is provide an amount of healing equal to your total HP."
This is widely known. Back in Heavensward, they had to hotfix Benediction to heal the full max HP value and not just the missing HP so that DRKs weren't getting left needing 1 more HP of healing. This is the one part that could use some clearing up in text, but it's not strictly wrong. A DRK with Walking Dead needs to be healed for 100% of their HP in order to dispel Walking Dead and save them from the Doom-like KO. The "bonus" is that if a healer is aiming to heal the DRK to full, they will achieve the dispel condition on the way.

And as for "being confusing to new players," that applies to everything. A brand new healer that hasn't read up on tank abilities won't know what Holmgang or Hallowed Ground or Rampart or anything is.