Why did Ya'akov repeat the names of all those who were buried in the Me'aras ha'Machpeilah?
Ramban: He stressed the importance of the location in order to encourage them to fulfill his request and bury him with Z'rizus (alacrity). 1
In spite of all the hurdles that they would encounter.
Why did he say "they buried Yitzchak", seeing as he personally had buried him?
Ramban #1: Because Eisav was also involved in his father's burial, and he did not want to mention him at this point.
Ramban #2: Because he would have to add 'and there they buried Rivka his wife'; so he combined them and wrote briefly "there they buried Yitzchak and Rivka his wife".
Why did Ya'akov find it necessary to point out that he had acquired his portion in the Me'aras ha'Machpeilah by burying Le'ah there?