It is hinted that in the future, Tsuna does get together with Kyoko.
Tsuna-ni is a nickname, meaning "big Tsuna."
After Tsuna defeated Byakuran, he and his family returned to the past.
We only know that their future selves get into a relationship with each other. We don't know if they married each other.
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.
Yes, when Tsuna is hit by the Dying Will bullet, he always "reborns," therefore leaving him in only his underwear.
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.
In chapter 352(at the end of the chapter),Tsuna found out that Reborn wasn't actually a baby. In chapter 353, Tsuna is still thinking about Reborn's adult form.
Byakuran and Tsuna start battling in episode 200 and the fight ends in episode 202.