As you may have already noticed, characters in DBZ often have meaningful names. For instance, saiyans all have a type of vegetable referring to their name. Examples are-
Bulma's family all have names that relate to undergarments.
Dr. Briefs- Briefs
Frieza's family's names are all relating to cold.
King Cold- Cold
You'll notice a lot of this throughout DBZ.
At the end of Dragonball GT, Goku goes away. You see descendants of the Z team in the future fighting in a tournament (I think).
Piccolo actually does a permanent fuse twice in DBZ, once with Nail, and later with Kami.
Gohan spends a year in the Room of Spirit and Time. That's how he became a super-saiyan.
Vegeto (Goku and Vegeta) is a permanent fuse. They use it once, and Majin Buu absorbs them. This splits them back into two.
Goku became SS4 when he heard Pan cry.
Trunks gets his sword from Tabion, after defeating the monster Hilderon.
Tien, Piccolo, Yamcha, and Chiautzu got past Snake Way faster than Goku did. They also did both tasks faster, too.
Krillin wishes for hair later in BDZ.
Uub, the reincarnation of Buu, actually stood his ground with Goku until Goku started flying. Uub can't fly.
Akira Toriyami, the creator of Dragonball and Dragonball Z, did not name the Kamehameha energy beam. His wife did.