1)
Why is the Simchah "Bo" (in Hashem)?
1.
Radak: We recognize that the salvation was from Him, for we trusted in His Kadosh name.
2.
Malbim: Hoping in Hashem is unlike hoping in man. If one hopes in man, and he is not saved immediately, he is sad, for he does not trust strongly. Perhaps he will not be able to save him or want to save him! In Hashem we rejoice, even if what we hoped for did not come immediately, for we trust in Him strongly. Surely He will save us, for His Kadosh name is called on us - "v'Shimcha Aleinu Nikra Al Tanichenu" (Yirmeyah 14:9).
