Andrey and Natasha

Volume II part III chapter 23. 
1/ Natasha is OK so far. I know she's supposed to be pure and lovely and charming, but for some reasons I'm not a fan. Too loud and noisy? Too talkative? Or maybe it's me, I don't even adore Elizabeth Bennet the way many people do. 
2/ Tolstoy's a magnificent artist- both the descriptions of outer scenes and inner thoughts are sublime. As in life, his characters do things inconsistent with their usual selves, contradict themselves, change, grow... without any sense of betrayal. They seem more like people, full of life and with control over their own actions, than characters created and dictated by an author. However, I do have issues with 1 scene (chapter 2, the same part) that I find a bit contrived- where Andrey, staying at the Rostov family, can't sleep and opens the window to overhear from above a conversation between Natasha and some others, and a short while later, also hears what Natasha says aloud to herself, which sounds a bit silly. 
Then later, at the ball, it feels slightly contrived again when Pierre suggests that Andrey invite Natasha to dance. 
This 2nd point might be defended that Pierre, as a friend of family, promises to help Natasha at her 1st ball (i.e she's out) and therefore asks his close friend Andrey. The 1st point, I suppose, can also be defended, but I'm not entirely convinced. Maybe the problem with it is not only that Andrey happens to be there to hear what Natasha happens to say, but more because of what Natasha says. 
3/ Andrey's disinterestedness in political work after he falls in love is convincing. I speak from personal experience.
4/ Andrey's and Natasha's kind of love is love at 1st sight. However, it's not a short, hasty courtship. The marriage is delayed for 1 year. 
5/ I'm curious about what Natasha and Liza have in common- the people 1 person has fallen in love with must have something in common, don't they? What is it, in this case? Beauty? Vivacity? Charm?