Why does it mention Esav, but Yishmael was not mentioned?
Radak (3): Yishmael was born to a Shifchah, and Hashem told Avraham to expel him.
Why does it mention giving Har Se'ir to Esav?
Malbim: It was proper for him (he absorbed the filth).
Why does it mention descending to Egypt?
Malbim: That was the smelting pot to refine Yisrael amidst the harsh slavery, to enable putting Shechinah on the entire nation, constantly.