1)
Why did he say "Yagel Libi bi'Yshu'asecha"?
1.
Radak: This corresponds to "Tzarai Yagilu Ki Emot." When You will save me, my heart will rejoice and they will mourn.
2.
Malbim: Gil is Simchah over a good that he never hoped for and sudden good tidings. Even though I trusted in Your Chesed, so the salvation is not a Chidush to me, my heart will rejoice in Your salvation like Simchah over something that he never hoped for, for I am not worthy it.
2)
Why are there so many expressions of trust in and thanks to Hashem?
1.
Radak citing Shocher Tov: There are four consolations corresponding to the four screams ("Ad Anah
