Kakashi's teammate from the Uchiha clan. See more here; http://naruto.wikia.com/wiki/Obito
Obito dies in the series Naruto
obito
Naruto is an anime series created by Masashi Kishimoto. The character Obito is an antagonist and is part of squad 7 (Team Kakashi). Obito used the name Madara throughout most of the Naruto series.
the fourth hokage
Because he felt that he was powerless to save him when Obito had died.
Yes, he is Obito
Obito is Kakashi Hayate's old team mate who was supposed to be dead in a Bandit fight .
Technically Obito lost his fight against the fourth, Obito managed to force 4th to flee with Naruto, but during their later struggle 4th defeats Obito buy teleporting to a kunai behind Obito
In the past Uchiha Obito and Kakashi were teammates under the Fourth Hokage. During a mission in the war against Hidden Rock, Obito was killed.
Nothing suggest that.
yes
Yes it is true that Obito Uchiha is tobi as shown in Manga Chapter 599