1)
Why does it say three times "vi'Ydatem Ki Ani Hashem" (also verses 38 and 44)?
1.
Malbim: They will recognize Hashem in three matters. (a) When He takes them out of Galus with a strong hand and selects out the sinners and Erev Rav (38). (b) Here, when He brings them to Eretz Yisrael and fulfills a second time His Shevu'ah to the Avos. (c) Refer to 20:43:1:1.