1)
Why does the Torah insert the (otherwise superfluous) word "ha'Nega"?
1.
Sifra: To teach us that it is only if the garment become one stage dimmer that it must be removed from the Beged, but not two stage. 1
1
See Torah Temimah, note 234.
2)
Why does the Torah write "Vekara Oso Min ha'Beged" and not simply 'Vekara es ha'Beged?
1.
Sifra: "Oso" teaches us that he must make a substantial tear in the garment, and "Min ha'Beged", that he must remove the torn section from the garment.