1)
Why does the Torah list Binyamin seventh, and Yosef at the end?
1.
Hadar Zekenim #1: It wanted to list first the Bnei Leah, and then the Bnei Rachel, 1 but to end with Yosef in order to elaborate on him.
2.
Hadar Zekenim #2: The Torah never lists the Shevatim in order of their birth. Rather, it changes the order [to show that they are all of equal importance], 2 to prevent the Bnei Leah and the Bnei Rachel saying to the Bnei Shefachos, 'We are more important than you.'
1
Oznayim la'Torah: Then the Bnei Bilhah and the Bnei Zilpah - in the order that Yaakov married them.
2
See Rashi to Bamidbar 27:1.