You guys are giving Kaname more credit than needed on the whole Yuuki seduction thing. I think the theory of him merely playing with her just makes him seem cooler than he really is. Yuuki is Kaname's one weakness. He really -does- want to be with Kaname forever, and in a moment of weakness (red eyes straddling etc) he thought to make her his eternally. And of course when came to his senses he said "that's enough of that"... he played it off like it was all his game in the first place. He often plays it off as he's playing with someone's mind when it might seem like he doesn't have complete control of a situation, examples including when Yuuki was demanding that Kaname acknowledge that Zero didn't kill Shio (or whatsherface) and whenever it seems that Zero might be protecting Yuuki more than he is. (Remember.. its my blood that flows through you so it's really me protecting her) of course I think this just makes him cooler. XD
As for the parent-suicide thing.. It really is a tossup.. It could be that he killed his parents for more power (which I think is unlikely) or saw his parents get murdered and is now working towards ultimate revenge by getting stronger and manipulating everyone. (Sexier older version of Sasuke?)