Well as a non-Kanaima myself, the only thing I can really say about it comes from having read that book in the past, but keep in mind that the writer was also a non-kanaima and therefore can’t be 100% completely and truly accurate.
Kanaima, aside from their traditional roles as revenge shamans, are predator-shamans, they assume the spirit of the hunter, calm and steady at first, but as they continue stalking their targets they grow more excited and hungry, therefore when they finally get to the target they torture them like they because of the lust of the hunter.
Kanaima drink the corpse as a way to satisfy their predatory hunger as well as for the benefits of it that aren’t really elaborated upon other than a longer lifespan and some other stuff.
Again the knowledge on Kanaima here is probably full of blinds and half-truths given to the writer by the Kanaima themselves so the only true way to learn about their magic is from them directly.
As for the methods, they use poisons and curse bottles, as well as poisoned and cursed arrows along with causing fear in the prey to get the job done, and a stick to drink from the corpse once its decomposed.