I have the grinder attachment that was supposed to also make baby food. I found that my immersion blender worked much better and got a smoother consistency. I might try the grinder again but that's been my experience so far. The blender was also easier to clean.
Hmmm... Never tried it. I do make a carrot souffle where I cook the crap out of them and puree them in my mixer. It does a really good job with that so I'd say give it a whirl. No harm if you already have the mixer.
Re: Kitchen Aid Mixer for baby food?