Dorohedoro/Headscratchers

Anything a Magic User does with magic cancels as they die, right? Does this apply to their (unused and stored) smoke as well? It seems like it must, otherwise Dokuga would have been left with useless smoke after he killed the healers. To be fair, it could be that they were just guarding the smoke, which came from others in their guild, but it seems unlikely that none of the smoke came from them (they were guild members who presumably specialized in healing magic). Also, Fridge Horror: If Noi dies, does every wound she healed except for ones caused by someone else's magic come back? Sure, she'd already be dead so it wouldn't really matter for her, but Ebisu would basically disintegrate, no? Or is healing magic, like curse magic, exempt from No Ontological Inertia?
Noi has actually died for a few minutes numerous times and nothing like that ever happened. It can be assumed that this kind of stuff happens when the Devil Shaped Tumor is destroyed, severely damaged, dies of starvation when it's magic user host dies or is taken out of the body (vide En's mushrooms rotting even if Kai preserved the Tumor and became it's new host.
When you think about it, Asu/Kawajiri's magic does not make any sense at all. Every other moderately powerful magic user could do the same by summoning a door - even Ebisu could do it!
When Shin exterminated the Hole's anti-magic militia, why did no one form a new one after he disappeared? Even Kaiman and Nikaido could do that.
Does the title "Dorohedoro" actually mean anything?