#1 -- I would say that the naming convention should reflect the content of the playbook. So if you see it taking on a specific theme, barth forth apocalyptica related to the theme. Also if you feel that your theme seems too diverse from the other needs and wants of the play-books, don't stop yourself from going back and refactoring it until it isn't.
Names: Haunt (maybe location specific rather then hunter), Returned (maybe there are contingencies on the return that force... abhorrent behavior), Ghoul (a focus on the morbid), Cadaver (maybe it's less about being a specific person, and something more like a body-jumping essence). Depends on the theme, I like many the previously mentioned too, including revenant. Also: The Morgue.
#2 -- I might say that you should take a strong look at the faceless, it is already focused basically on the same thing as your stated intent here. It wouldn't take much to either take insights from its design, or just just use it as your design. The Faceless could easily be "converted" into a back-from-the-dead vengeance seeker, I might go as far as to say it already is.
Worthy Mentions: Be careful having a Sharp based class, there are very good design reasons why the actual play-books moved away from this stat. It is already universally useful and universally powerful. Allowing someone to sit on top of it like a Battlebabe on cool or the Gunlugger on hard is asking for them to be much more potent then you might expect. Having any character based around revenge is already placing a lot of emphasis on Hard. Undead and Sharp don't tend to mix conceptually, if you consider that their interactions with other people will be colored by disgust or wariness. Sharp != Detective. Weird / opening your brain is a better sleuthy. You might want to take a look through the other playbooks, The Grotesque in particular might offer some cool insights, it managed to be an isolated playbook while at the same time offering a lot of interaction. Either way, Good luck in your pursuits, I hope you figure something out that's cool for you and your table.