My point was really to say that - it's not like you have to be shooting in RAW format ALL the time. Nor is it to say that you should always be shooting in manual mode. Especially for folks just getting started in DSLR (myself included). Even the last show that I shot I was in Av mode for a time and got plenty of great shots without having to tweak settings on a moments notice. Post processing is a whole other ballgame. I think it makes more sense to learn the camera settings/modes first and everything else that goes along with that. Using JPG's initially you'll save space and PP time on the backend. Again, like I mentioned before, it all depends on what you're shooting. RAW certainly has its place.
Absolutely. There's nothing wrong with shooting in aperture-priority mode, especially when combined with exposure compensation. In fact, it's often a better approach! The only mode I never use is "program."
I also agree, the most important thing is understanding the principles of photography and how to apply them. It's not rocket science, but there is a lot to think about.
When I first starting using a DSLR I never shot RAW, only JPEG. It wasn't the biggest mistake, but now I really see the benefit, particularly if there's a lot of shadow detail or the image is underexposed. When I tried to bring out the detail by dodging or some other means on a JPEG, I often got noise and compression artifacts. Now I shoot RAW + JPEG, but only keep RAW files of my better images.