Perfectly agree with that. And that's exactly what I'm doing so far: working for someone could be useful for improve yourself not only in what you'd like to do: side projects will benefit from this, believe me. I noticed improvements event in terms of analysis of problem solving.
I absolutely agree with you!
After 10 years of work I only realized in the last few ones that those things you listed are the only to care about. Personally I always try to learn and apply to new projects, and not giving over 100% makes me feel quite comfortable even in those difficult relations expressed in the main thread. It's really important when you work for a company for a long time: you may learn all the dynamics between your colleagues but you cannot avoid some kind of behaviours...