HAHAHA at all the "2 bags of peanuts" comments!
And regarding the wheelchair thing, correct me if I'm wrong, but my understanding was that they take the person out of the wheelchair, put them in the airplane seat, buckle them in, and fold up the wheelchair and store it. They're not just rolling around the aisles in their wheelchair - the safest spot for everyone is in the airplane seats. So, no, they don't automatically get first class.
Admittedly, I haven't flown very much, but I've never seen anywhere they could buckle down a wheelchair safely (you know, like the brackets they have on buses).