What is the meaning of "va'Yir'em"?
Rashi (from Sotah 46b): He saw that there is no [and will not be any] trace of good in them or their seed. Radak - therefore, it was proper to remove them from the world.
Why did Elisha curse them?
Radak (citing Sotah 46b) #1: Since they disgraced him, he put his eyes on them, and they were punished. Wherever Chazal put their eyes, death or poverty resulted.
Radak citing Sotah 46b) #2: He saw that all of them were conceived on Yom Kipur. Radak - since they came from sin, it was proper that they die. This is why they wantonly disgraced him. He did not curse them due to their disgrace of him.
Radak (from Sotah 46b) #3: He saw that they grew long hair like idolaters.
Radak: Refer to 2:24:1:1.
Malbim (23): Because they came from evil parents [who taught them to mock Nevi'ei Hashem], he removed weeds from Hashem's vineyard.
Was Elisha justified to curse them?
Radak (from Sotah 47a): No. Elisha fell sick three times. One was (punishment) for inciting bears to kill the youths (through his curse), one was for casting off Gechazi with both hands, and one was the sickness he died from. We learn from "ve'Elisha Chalah Es Chalyo Asher Yamus Bo" (13:14).
Why does it say "Shetayim Dubim"?
Radak: It says Shetayim (feminine) because they were female bears. [Even so,] it says Dubim with a Mem at the end, just like "Gemalim Menikos" (Bereishis 32:15), even though they are females).
From where did the bears come?
Radak citing Sotah 47a #1: This was a miracle. A forest already was there. The bears came miraculously.
Radak citing Sotah 47a #2: This was a miracle within a miracle. Both the forest and the bears came miraculously.
What is the significance of 42?
Radak citing Sotah 47a: Due to the 42 Korbanos that Balak brought, 42 children of Yisrael died.
