Probably at one time. How else could he have been created?
There was this one time where he got so mad at Orochimaru that his whole skin peeled off and the Kyuubi partially came out making the mini kyuubi, but so far it hasn't.
Almost everyone does already know about Kyuubi. But when everyone sees Naruto using Kyuubi at the most he's ever used it was during the battle with Pain, around chapters 427-444. He goes 6 tails around chapter 436-438, and uses all 9 after that. But he is stopped by someone...
Kyuubi is Japanese word. 'Kyu' means 9 in Japanese. So Kyuubi is 9 tailed
the kyuubi is the nine tailed demon fox yodaime sealed within Naruto.
Not necessarily "useless", but he is less powerful without Kyuubi.
No. Kyuubi strongly resents the fact that the Yondaime managed to seal him.
Chapter 299 was the first time Naruto went kyuubi.
Kurama
Uh. Hell NO! What gave you that ridiculous idea?! If he WAS female wouldn't his title be "Kyuubi no Vixen?" Duh he's male. No female could ever have a voice that low. Don't you think it'd be SLIGHTLY awkward if Kyuubi told Naruto he was female? Can't you imagine the awkward silence that would follow? I sure can! Notice on sites he's listed as the Demon KING. IF he WAS female his title would need to be the Demon QUEEN. Plus it just makes more sense for him to be a guy. Not to be sexist or anything (I'm female too you know!) but typically in most societies males are viewed (and favored) as the more powerful sex over women, and Kyuubi is centuries old. He must have been human once if he's this intelligent.
Almost everybody
Kyuubi
Um...O.o No. Kyuubi is the title of the bijuu sealed inside of Naruto. Naruto's mother was Uzumaki Kushina.