Too big! Seriously, this post contains too many elements to readily reply to in a coherent way.

So I'll just address this:

I can’t read these two quotes side by side and not be confused.

To me, those two quotes are both fair, and the combination of them indicates the reason why you need to acquire a habit of thinking in a way that is both definite and positive: to keep fear in its right place, which is mostly NOT putting on the brakes.

and this:

But that's not what 'goal setting' feels like to me. I feel increasingly awesome as I get closer towards a goal, and once it's done, I keep feeling awesome when I think about how I did it.

Me too. But we need to acknowledge the many, many people for whom this is not the case; People who believe that there's something basically wrong with themselves and use any failure as an opportunity to punish themselves. These people need to, as Bradbury says, change who they are, before they can experience goal setting / achievement as 'awesome'; As long as they think of themselves as bad or inadequate, their evaluation of their achievements will continue to conform to that.

Process goals, or systems, are probably better than outcome goals. Specific and realistic goals are probably better than vague and ambitious ones. A lot of this may be because it’s easier to form habits and/or success spirals around well-specified behaviours that you can just do every day.

Not only do I agree with this wholeheartedly, I want to mention that most of my major creative progress is directly attributable to goal-setting behaviour.

One thing that's implied, but not directly stated in your post is that it's best to set goals that you will occasionally fail at (cf. Decius' reply to cousin_it re: inconsistent reinforcement)