Since a few of Kitsouille question were interesting I chose to answer some of them:
if someone had the power to swallow/digest/absorb/store inside a whole human being, and that person wanted to fight crime, would they be ok with themselves if they actually ate other human beings, would they gross themselves out, would they limit themselves to eating inorganic materials, would they eat but spit out humans, would they digest humans, etc?
I'm pretty sure that if someone had the power of voring people and had enough morality to think that eating criminals are ok, but not enough to feel guilty, they might as well do it. You could play with his motivation or why he can eat people too: he could be a one-off mutation or his entire species necessitate to do it, or maybe he does it for fun or sport, or because he likes the taste, or he is fascinated by heroes and wants to be one too and he's just using what powers he has at his disposal
How would people react to a hero being able to do this, is this a hero at all, could people be against that person doing vigilante work at all, is the vigilante hated, does it grosses out the vigilante's fellow allies, does his/her allies forbid the vigilante from eating/killing people, etc?
It would depend on how the hero does it if he's discrete and tries to tell people why he's eating him and to look away if they don't want to see the guy getting eaten, or if he just appears in a street full of people and just eats random persons, or if he swallows his preys whole or in pieces. As far as his allies, as the word implies, they should support him, or at least tolerate him, especially if he needs to eat living beings, maybe less if he does so for the taste or because he can, but at least they should be happy about the fact that he's an ally and not an enemy.
As far as public opinion does, it would be the usual spectrum going from "That thing is disgusting, we should kill him quickly" to "I want to be eaten by him but I don't want to be a criminal, what can I do?"