actually, for kyuubi dying, i always thought that Kyuubi was simply appriciating Naruto's couarge for threating him, I don't think Kyuubi knows either what happens to him if Naruto dies. I'm pretty sure that no one has the slightest idea how this sealling thing works, which is why naruto wasn't killed as a baby.

and a on a diffrent matter, they have to take care of the kyuubi, I don't think he would be there all the time, they should get into a conflict one time, or at least part ways. you know, like any other shonen series.