A lot fewer quests require killing than you'd think. You don't go to areas with deathclaws or hell spawn infested buildings.
True. A no kill playthrough isn't impossible and will definitely give you a fresh look at the game. Be prepared to run a lot, be prepared to sneak a lot, be prepared to walk away from a couple of quests (really though, only a couple).
I did a "no personal kills" playthrough, no problem. I did "cheat" because I wanted to do companion quests so I had companions for a lot of the game, and of course they are all psycho berserko no matter what you do so ... yeah. Violence happened. My character never did anything but block though.