1)
Why did Moshe not explain to Par'oh why they needed to take the animals with them?
1.
At this point, Moshe was informing Par'oh as to why the women and children had to accompany them, as that was the main thrust of his claim. When, after the plague of darkness, Par'oh allowed them to go with the sole exception of the animals (see 10:24), Moshe explained to him why they needed to take the animals out too.
2)
" .. ki Chag Hashem Lanu". Which Chag wa Hashem referring to?
