1)
How did they resemble horses?
1.
Rashi: Their speed was like horses.
2.
Malbim: They were like horses at a time of war coming to conquer the land.
2)
What do we learn from "uch'Farashim Ken Yarutzun"?
1.
Malbim: A horse itself has Gevurah to run noisily. A man who rides on a horse is called Parash. It runs faster when a man forces it to run. Hashem's decree forced the locusts [to go very quickly].
