What are the implications of "Vehiflah Hashem es Makoschsa"?
Rashi: It implies that He will make our affliction more wondrous and different [than those of other nations].
Targum Yonasan: It implies that, when the Makos strike Yisrael, Hashem will hide his Ru'ach ha'Kodesh from them. 1
Shabbos, 135b: Based on the same word in Yeshayah, 29:14 "Lehafli es ha'Am ha'Zeh", where the Navi continues "Ve'avdah Chochmas Chachamv", it implies that there will come time when Torah will be forgotten from Yisrael. 2
Temurah, 3b: Based on the Pasuk in Ki Seitzei, 25:2 "Vehipilo ha'Shofet" - in connection with Malkos, "Vehiflah" refers to Malkos, and, with reference to the previous Pasuk here, it teaches us that someone who K'lalos by the Name of Hashem 3 is subject to Malkos.
Since the word "Vehiflah" has connotations of 'hidden'. See Na'ar Yonasan. See also Rashi, Shoftim 13:18.
See Torah Temimah, note 43, citing Shabbos, Ibid., that wht it really mens is that there will not be Halachah Berurah and Mishnah Berurah in one location. See Torh Temimah, note 43.
See Torh Temimah, note 44.
What is the significance of the fact that the Torah write here "Vehiflah Hashem ... " and the Navi in Yeshayah 29:14 "Hin'ni Yosef Hashem Lehafli ... Haflei va'Fele ... Ve'avdah Chochmas Chachamav"?
Rashi (in Yeshayah): It teaches us that the death of Tzaadikim is twice as hard as the Churban Beis-Hamikdash.
What are the implications of "Chalayim Ra'im ve'Ne'emanim"?
Rashi #1: The illnesses are faithful to chastise you and to carry out their mission.
Rashi #2 (in Machzor Vitri, citing Avodah Zarah, 55a): They are evil when they perform their errand and faithful in their oath - When an illness comes upon a person Hashem makes it swear that it will only depart on a certain date, via a certain doctor and by means of a specific medicine.
Rashbam and Targum Yonasan: They are faithful to remain on your flesh for a long time (until Hashem orders them to depart - Rashbam).