1)
Why does it return to discuss the lineage of Bnei Kehas?
1.
Redak: The Sefer wants to teach his sons and grandsons.
2)
Here it omits Yitzhar ben Kehas, and it adds Aminadav!
1.
Redak, Malbim: Aminadav is Yitzhar - he had two names. In each place he is called by one of his names.
