Board Thread:Naruto Discussions/@comment-4646462-20160626012036/@comment-25549954-20160626063057

Chakra is a combination of physical energy produced from the cells of the body through excercise, meditation, and physical energy from mind, So chakra can be produced when the user wants it, it is not infinite, you can see it takes time to recover chakra, Sasuke's amenotejikara takes time because lot of chakra is consumed, in VOTE 2 Sasuke and Naruto returned to normal form after battling Kaguya. Naruto's sage mode is not just natural energy it is a combination of his chakra and natural energy, he balances his chakra with his natural energy to maintain his sage mode, at that time the tree was absorbing chakra, natural energy is abundant, his Sage mode will not be affected when he is in close vicinity to the tree.

Hagoromo has his own chakra he gave Naruto and Sasuke his chakra and the tailed beasts are not required for it.

Black Zetsu didn't absorb the chakra he transformed Madara's body to Kaguya. After Kaguya was sealed Madara was released.

Obito's ghost did what he had to before going to pure land, after someone goes to pure land their soul cannot be called back to earth but there are exception, those who have Rinnegan can summon them from afterlife (this is what Hagorom did) or by summoning impure world reincarnation technique (Kabuto's technique).

If the jinchuriki dies the tailed beasts return to life.