In my first playthrough, I played a steathly rogue with very few combat skills. This ended up being a mistake, since it prohibited me from taking on the many quests which required me to kill things.
You can do all the quests without making a single kill, except for one.
I haven't done it myself, but I believe you'll need to use 'Charm' a lot. Charm a baddie and let him kill another baddie for you.
Or drag hostile beings to guards or other volunteers that will do a job for you.
The only quest where this will not work is the spiders in the warehouse quest, as you'll always be left with one in there.
Yes, the food and water system is well done, I agree. It doesn't make the game more difficult for competent players, as they don't need to rest much, so they don't use food and water that much, but then it still adds flavour. For fairly inexperienced players the food and water requirement can indeed be a serious concern.
But cannibalism? Not for me, sorry. Maybe in a horror RPG, but in Eschalon this would seem misplaced.