I can answer a few of your questions for you:
Gnarrkhaz wrote:Why would Rainbow Dash blame Twilight for not being able to teach her efficiently? I see they've come a long way as friends...
Because Rainbow Dash believes she can't be wrong. And in the event it appears that she is wrong, it must actually mean someone else is wrong. It's in her personality/worldview.
Gnarrkhaz wrote:Why is Rainbow Dash totally relaxed not knowing the history of the Wonderbolts although the test is coming up and then after realizing she doesn't know shit she's totally baffled?
She's relaxed, because she's not used to being stressed. She's used to being awesome at everything and the mindset that comes with it. Realizing that she isn't awesome at this comes as a shock. (I've been guilty of this in the past.)
Gnarrkhaz wrote:Who the hell uses...clothing to teach stuff?
Rarity apparently. That seemed a bit forced to me, but it did make for some fun colorful eye candy for the audience. I may be able to draw a parallel, though. I once had a class where I had to memorize a bunch of stuff word-for-word. In order to do that, I used music. I would write little tunes, so I could sing the words I needed to memorize to myself. It helped. And since music falls under the "Art" category, it is conceivable that someone could utilize a different art form--like fashion--to help them learn.
Gnarrkhaz wrote:Did Rainbow Dash seriously expect to pass Twilight's test with the answers she gave?
This goes along with your second question, though it is a bit more extreme of an example. RD isn't used to needing the
correct answers to be awesome. She's used to using her style and attitude to be awesome, and being correct has never been a contributing factor to this. Again, she's simply unaware of the necessary mindset.
Gnarrkhaz wrote:Why does Pinkie rap?
See my answer to your third question. Also because Pinkie.
Also here's some
even better examples of using songs to help one memorize things.
Gnarrkhaz wrote:Why do Owlowiscious and Spike join Rainbow Dash in fooling around during class?
Spike is immature, so he will have a natural tendency to fool around. I agree that it is out of character for Owlowiscious. He should be much more responsible than that.
Gnarrkhaz wrote:Why the hell is Rainbow Dash such a bitch shooting spitwads at Twilight!?
This is harder for me to justify. However I just got done watching a Game Grumps episode where they talked about how they express their love by telling each other to f* off. This is similarly alien to me. Also Patrick did it to Spongebob that one time. I get the feeling that this sort of behavior represents a personality type that I've just simply never encountered.
I wasn't a huge fan of this episode, but now that I've taken this time to analyze it for you, I think I enjoy it a bit more. My own learning style is closest to Applejack's "You mean you don't already know?" -style. Pay attention in class and do the homework and you'll be fine. Try to cram everything into your brain the night before, and I really don't have any advice to give.