I was reading along and nodding away at so much of this. I wonder how much of this we don't want to believe, because it's easier to make excuses about why we're not good at something.
I feel like I could write a full post in response to each of these, but I'll try to keep it to just a couple of thoughts. Firstly, these reflect so many of the things I learnt from educating my girls and I always tried to remind them that repetition is the only real way to improve. I also used to work to find ways to make what they were learning enjoyable otherwise they weren't able to retain it.
The other thing that struck me, was your example for multitasking. While I'm with you that no-one really multitasks (the just switch between tasks) I will say that the music and study does work for a small few, but for a reason I've only recently discovered. Hubby used to play Metallica while taking exams and Angel focuses better with music blaring. Recently Angel was diagnosed with ADHD and part of her issue is that so much is going on inside her head, music is the only thing that quiets all that extra noise so she can focus better on the task at hand, especially if it's stressful or boring. So in their case, music actually acts to reduce the amount of distraction happening in their heads, giving them less to focus on.