Yes. In the Kakashi Gaiden Arc, Kakkō used Earth Release: Rock Lodging Destruction to try and kill Kakashi Hatake, Obito Uchiha, and Rin. Obito pushed Kakashi out of the way of a falling rock, and Obito's right side was crushed. As Obito did not give Kakashi a gift when Kakashi was promoted to Jōnin, Obito decided to give Kakashi his remaining Sharingan eye. Rin obeyed Obito's wishes, and transfered his Sharingan eye into Kakashi's injured eye. While the cave falls, Obito thinks about his teamates and how he never got a chance to tell Rin he loved her. Kakashi avenges Obito by killing Kakkō with a perfected Chidori.
No.
Because Tobi is from First hokage generation and Obito was from Kakashi generation.
Obito dies in the series Naruto
He comes back to life when they make a wish to Porunga.
He doesn't have one. It was never mentioned in the manga or anime, and if he did, it would have come up eventually.