The Kyuubi has a say when Naruto uses up all his chakra and wants some more. Fortunately for Naruto, the Kyuubi happens to like him more than he likes Madara and most likely Tobi, given the genjutsu he put him in 16 years ago. The Kyuubi is an illustration of the benefits of treating others the way you wish to be treated.
Peace
Hanzou gave them the title of, "The Sannin," which translates to "The legendary three ninja" according to Naruto wiki (it isn't a perfect source, but for that translation I'm comfortable as a reminder), "sennin" does mean sage, thus the So6P is also called the Rikudou Sennin. There's a difference in the words and respective translations, that's why Tsunade is referred to as one of the the Sannin for example, but she's not a sennin. Jiraiya, however, is both due to his knowledge of senjutsu.
Also, the first Senju was a descendent of the younger son of the Rikudou Sennin and the first Uchiha was a descendent of the elder son. During the Rikudou Sennin's life as I understand it, those clans didn't exist. I believe Tobi explains this to Naruto, Kakashi, and Yamato in Iron country while Sasuke is attacking the Kage Summit. Granted, this doesn't detract from our knowledge that the Rikudou Sennin had a powerful body and chakra based of what he left to his younger son. Further, when he was the Jinchuuriki of the Juubi, Tobi reffered to him as supra-human, which is what Tobi wanted. I believe that this is stated by Tobi to the 4 Kage at the summit when he reveals the Moon's Eye plan.
Nonetheless, I don't think that there's any proof that the Rikudou Sennin knew sage mode, and the that the Sennin term comes from his wisdom and knowledge of ninjutsu, etc. as well as possibly more practical matters of life and insight unrelated to ninjutsu such as peace.
Peace