Maybe. We don't know yet.
the naruto has ever made it is to 8 tails and that was by accident he made 9 tails but the 4th sealed it and reveled that naruto is his son so naruto was the 9 tails for a split second when pein sealed him in a rock sphere thing.
No.
Yes. when hinata is attacked by pein, naruto thinks she is dead and goes up to 6 tails in an instant. naruto keeps going to 9 tails, when he finds himself outside the gates of the kyuubi, and The 4th hokage appears, revealing to naruto that he had set it up so he appeared if naruto ever reached nine tails. he tells naruto he is his father.
naruto does become "happier"
Yes.
Yes naruto does go five tails one time, i dont know what episode though. But in episode 437 naruto goes six tails!!! the highest hes gone so far is ALL NINE!!!!!!
no it will never die until naruto is dead
yes he can get up to 3,994,555
yes he did but never showed episode yet but it will soon
No, not until now anyway. Naruto have reached to 8 tails when fighting Pain.
So far, no
No, that was a one time deal. Minato used some of his chakra to be able to speak with Naruto when the nine tails was beginning to take over Naruto. Minato only gave enough chakra to last for a short time and then for Kushina (Naruto's mother) who Naruto meets when he learns to control the nine tails.