The point about taking a ressie from another family who wants one is a valid one, and reason enough.
As for the others:
1) We did do a pre-opening CP breakfast last year and were not impressed. My son (and the rest of us) enjoyed Chef Mickeys much, much more.
2) When we got in, there were a lot of people milling around. There was some sort of tour going on, there were people strolling up Main Street. We took pictures in front of the castle. No one ever said anything to us or anyone else that I saw.
3) We had 8:10 ressies, and they took forever to seat us. We didn't get out until about 9:30.