its gokudera
Yes, when Tsuna is hit by the Dying Will bullet, he always "reborns," therefore leaving him in only his underwear.
Tsuna-ni is a nickname, meaning "big Tsuna."
Yukari Kokubun. Tsuna's seiyuu voices him normally and in his hyper dying will mode. (Quite talented of a person if you ask me.)
It is hinted that in the future, Tsuna does get together with Kyoko.
After Tsuna defeated Byakuran, he and his family returned to the past.
Giotto IS the first vongola boss. He changed his name to Ieyatsu Sawada when he went to Japan. He created the Vongola Family, which was first made to be a vigilante group to protect people. People mostly call him Vongola Primo. And he is also tsuna's great great great great (haha...did I put too many 'greats'?) grandfather, an direct ancestor to Tsuna.
Chrome kisses Tsuna in episode 51 on Hitman Reborn
We know that Tsuna eventually ends up with Kyoko.
Haru helped Tsuna with the X-burner.
Yes, he gets a pet called Nuts or Na-tsu, which is obviously Tsuna backwards.
Tsuna gets Natsu in "Katekyo Hitman Reborn!" during Episode 199, which is titled "The Future." In this episode, Tsuna receives a new baby guardian, Natsu, who is the future version of his younger self. The introduction of Natsu plays a significant role in the story as it highlights Tsuna's growth and responsibilities as a future leader.
Tsuna might not fight Byakuran at all. Uni clearly stated that she was the only one to defeat him and Tsuna in the future was either dead or in the time machine. Well, in the manga he is already fighting him and almost half dead.. Byakuran is way to strong.. [SPOILER ALERT] you have been warned Tsuna does in fact defeat(more like pulverizes) Byakuran and in the latest release Tsuna and his Family have returned to past, also the future Tsuna never died he was put into a special state that gave his enemies the impression of him being dead, so that the Vongola or any of Byakuran's opponents could have an upper hand.