there is a 3rd part of it but it is named dbz buu fury
There is never going to be a Dragon-Ball z legacy of Goku 3 but there is Dragon-Ball Z Buu's Fury which is basically what happens after Dragon-Ball z legacy of Goku 2.
In the heart of the north temple
According to Dragon Ball Wiki, yes, there is one, but it is called Dragon Ball Z: Buu's Fury. It is still the third part in the trilogy, even though it doesn't have the "Legacy of Goku" title. Source: Dragon Ball Wiki
No
Goku.
There is a Gt movie called A Hero's Legacy and it is about Goku Jr., and Pan is alive and Goku shows and talks to Goku Jr.
No...
pretty much.... except better features and new story line
he meets him in DBGT in the movie a hero's legacy
Goku and Goku Jr. meet in the DragonBall GT movie, "A Hero's Legacy."
simple just complete all missions
gohan,piccolo,vegeta,trunks,and goku\kakarot