Incapacitate them with magic, then stomp their faces in with your boot in a purely mundane, if quite messy, fashion.  Remove your boot.  Burn or otherwise render it useless as evidence in the mundane justice system (magic helps here, too).

Wardens use swords instead of boots, but swords draw attention, and are cliche.

The Custom Stunt list is not meaningfully fact-checked.  The existence of a stunt there should not be taken as indication of RAW.
If the power itself does not specify an action type, then the Shapeshifting section's intro states it to be supplementary.

One power I've found worth paying attention to is Cassandra's Tears. Sure, you can stop NPCs from believing what the character says, but you need to watch your players and make sure that they're not meta-gaming too much, especially if you have a larger player group and less need of NPCs.

The best way to handle this is with Compels.  Everyone likes FPs, even metagaming munchkins.  Often, especially metagaming munchkins.

A strict reading of Incite Emotion combined with Emotional Vampire may allow for two simultaneous mental attacks (or an attack and a maneuver/block) against the same target, seriously messing with the action economy.
While I do believe this to be a valid literal interpretation of the rules, I also believe that it is a dangerous one where game balance is concerned.  Tread carefully.

Aside from that, polkaneverdies and wyvern both gave good advice.

I'm pretty sure only the first full feeding is fatal.

That's a definitional issue.
A 'full' feeding is, by definition, almost universally fatal.  The first instance of such is no exception, but it's also no an exception to the 'almost'.

Only with time, dedication, and practice (typically including at least a few casualties) can a WCV even hope to learn the control it takes to cut short what would otherwise be a 'full' feeding, and many never achieve that (though few probably put in the effort; it's not a popular thing to do).
Some unusual circumstances might greatly assist the WCV, or take the matter entirely out of their hands, however.
As mentioned, a prospective victim might simply possess so much life force that the demon can have its fill without killing.
Alternatively, the act of feeding might simultaneously be the final piece that seals True Love between the WCV and their meal, cutting the meal short at the last possible moment and leaving the succulent morsel on the verge of death's door, but not quite gone.

High rolls should not be bad for the character who achieves them.

That's when the Choice is made, yes, but the Choice is not necessarily where NPC-dom is decided.

Evothaum IS Evocation with a differing set of available (narrative) effects.  It uses the rules for Evocation, including those for specializations and foci.