Why was Aharon instructed to perform the plague of lice, and not Moshe?
Rashi and Targum Yonasan: Because it entailed striking the ground, which would have demonstrated a lack of gratitude, bearing in mind that the earth protected Moshe 1 when he buried the Egyptian in the sand (see Shemos 2:12).
Gur Aryeh (to 7:19): Why would that make any difference? (The earth is but an inanimate part of Creation!) Rather, the Torah is teaching us proper conduct -- "Do not throw a clod of earth into the well from which you have drunk" (Bava Kama 92b).
Why did Hashem not warn Pharaoh about the plagues of lice, boils and darkness?
Ramban (to 8:15): He only warned Pharaoh before the Makos that resulted in human death or destruction. 1
Rashbam and Seforno: Refer to 7:26:1:2**.
See Ramban DH 'u'Mah she'Amar.'
What is the significance of the fact that the first three plagues began by striking the water (see 7:20 and 8:2) and the ground?
Oznayim la'Torah: Because the Egyptians forced Yisrael to make mortar and bricks out of earth and water, Hashem brought on them the first group of Makos by striking the earth and the water.
What was the significance of 'De'tzach' (the first set of three plagues, which ended with Kinim)?
Oznayim la'Torah (citing Abarbanel): It was to teach Pharaoh that Hashem exists 1 - by demonstrating that He rules over the water and over the land, and that He created their 'offspring' -the blood from the water, the lice from the earth, and the frogs from both.
Why does the Torah talk about the Kinim as if they also came to Eretz Goshen, and as if they affected Yisrael as well?
Oznayim la'Torah (citing the Rambam and R. Yonah in Perush ha'Mishnayos in Avos): There is a tradition that the lice struck Yisrael too, 1 only they did not cause them to suffer. 2
Oznayim la'Torah cites a Midrash Rabah (in connection with Yaakov's request to Yosef not to bury him in Egypt) to the same effect.
Oznayim la'Torah: Perhaps this was to harden Pharaoh's heart - as he would otherwise have let Yisrael go when he heard from his magicians, "Etzba Elokim Hi!" (8:15). See also Oznayim la'Torah, DH "va'Tehi ha'Kinam."
