How does Naruto beat Zabuza?

Answer 1

He does not "beat" Zabuza. He and Sasuke were fighting Haku while Kakashi was fighting Zabuza. Sasuke is put in a near death state by Haku's Demonic Ice Crystal Mirrors. Naruto was devastated at the sight of Sasuke in that state that he used the Nine Tailed Demon Fox's chakra for the first time. With that chakra Haku was amazed at the power and was ultimately defeated by him. He then asks Naruto to kill him because he states that he serves no further purpose to Zabuza and that killing him would be best. Right before Naruto strikes him with a kunai knife, Haku notices Zabuza about to get killed by Kakashi's Lightning Blade and rushes in to protect him. Kakashi kills Haku instead of Zabuza. Zabuza states that he did not care about Haku and Naruto was enraged. He spoke to Zabuza about how Haku felt, and that he was trying to achieve Zabuza's dream for him. Zabuza ends up crying, touched by Naruto's words. He then finds out that Gato (the person who hired him) has betrayed him along with a crowd of other people. He uses a kunai to slice through the crowd of people, but was heavily injured doing so. He then knocks Gato off the bridge, killing Gato. Knowing that he would die because of his injuries, he asks Kakashi to bring him next to Haku so that they would die together. They are then buried next to each other.

Answer 2

Naruto has not killed Madara (yet). Manga/anime is still ongoing. It hasn't come to that point (yet).

Answer 3

[Spoiler] Madara Uchiha is already dead. The person behind the mask is an impostor claiming to be Madara Uchiha.

Answer 4

Naruto destroyed the last Path, Deva Path, using shadow clones and a well-timed Rasengan, as Deva was able to repel any of his attacks, but had to wait five seconds in between each.