Step 1: Deathwatch at-will is good for telling undead from the average joes, and stays in.
Step 2: I got nothing.
Step 3: Speak with Dead is excellent and stays in.
Step 4: The ability to crit on undead stays from Death, but I'd like something beyond that.
Step 5: Got nothing.
Step I: The damage bonus could be against Undead, and Outsiders (and maybe Horrors) who participate in perverting death which sounds thematically appropriate for "defenders of peaceful death".
Step II: There's nothing wrong with people who don't like Undead being able to exert their will over them, so Dominate is fine. For the other spell Consecrate is a logical choice, or maybe something like Righteous Aura for that "badass with magic" look.
Step III: Either Glyph of Protection I or Prayer are logical replacements for Animate Undead.
Step IV: In this particular instance no spell jumps out at me. Maybe Light's Grace.
Step V: Again, Dominate Undead is fine. For the other Purge sounds lovely.