After issuing the warning about the plague of hail, why did Moshe advise the people to gather the animals and the people under cover?
Ramban: Because the objective of the Barad was to destroy the crops, not the animals and people. 1
Seforno: In order to save the slaves who shepherded the flocks. 2
Why did Hashem constantly divulge his plans to Pharaoh, something that human kings don't do?
Rashi (in Iyov, 36:22): Unlike a human king, who needs to hide his plans from his enemies, lest he utilizes his knowledge to outwit him, Hashem knows that nobody can upset His plans, so He has no reason to conceal them; whereas by revealing them, He offered Pharaoh a chance to do Teshuvah.
Why did Moshe warn to take the animals into the house before hail, but not before Dever?
Moshav Zekenim: If they took the animals in before Dever, nothing would die! In any case, the hail would destroy vegetation.
According to the Ramban (refer to 9:3:1:2), Dever killed also animals in the house.
Why do we say (Nega'im 12:5) that the Torah is concerned for the money of Yisrael? We find here that it is concerned even for the money (animals) of Nochrim!
Moshav Zekenim: Also here it was for the need of Yisrael