Well, one thing is for sure. There was some doubt about the three of them being siblings. But if the translation is right, they are. So, now, both in the manga and the anime it has been stated that they're related.
We will never know how the Kazekage died, but that's something about the Sand that know we know for sure.
And you may now ask, who cares? [img]i/expressions/face-icon-small-tongue.gif[/img]
And great job Natsumi... really fast.