Why did he mention Yakov's descent to Egypt?
Malbim: This was unlike the other afflictions, which were due to sin. Yakov descended in order to do good to you in the end.
What did Yakov scream about when he descended to Egypt?
Radak: The verse is abbreviated. When Yakov came, and stayed a long time, and a new king made decrees against Yisrael, they screamed to Hashem.
Why is he mentioning Moshe and Aharon again?
Malbim: Hashem did not save you via a king, rather, via His Nevi'im.
Moshe and Aharon did not bring them to here. They did not cross the Yarden!
Radak: Moshe and Aharon rebuked them and taught them to go in the way of Hashem, therefore [Yisrael] entered the land. It is as if Moshe and Aharon settled them here.
