Yes, she is a hero, which places her squarely at the top of the world. You can't go and save the world, and expect to be shoved off into obscurity if you live; if you died, hell, you would be venerated as a godlike figure. There's no winning; you either die, or you deal with the whole of the world's population. There's so many instances in FFX-2 where Yuna is incapable of acting on what she really wants to do because of the expectations people had of her. If she really wanted to avoid the politicking, she'd just not listen to anyone, and yet she does. However, there are several figures in the real world that can be compared to Yuna. Okay, so they haven't quite saved the world, but they are world leaders, and have incredible power and influence, enough to get millions of people to listen to them.
Well Yuna listens to other people because, despite the fact she's such an important figure, she's still humble and human. She could obviously and easily flaunt her position but she just wants peace and quiet.

Also, at the time of Yuna's concert, those leaders had vanished. No one had any idea why they were gone...they just knew war was about to break out and their leaders had abandoned them. So essentially all these people only had Yuna ot turn to.

Your other two points are agreeable enough. As for how much Shuyin's and Lenne's tragedy effected you, that's purely subjective.