It should suffice that Yaakov would bring the food, so Yitzchak will think that he is Esav, and bless him. Why did she add "and he will eat"?
Malbim: This is one of the three conditions for the Berachah to be fulfilled; (refer to 27:4:1:4. Yaakov will fulfill Kibud Em, this is his preparation.)
Why did she not say 'Tevarechecha Nafsho'?
Ha'amek Davar: It was not Yitzchak's desire (Nefesh) to bless him. In any case, he will bless him.