Why does the Torah add "Vaya'as Hashem ki'Devar Moshe"?
Oznayim la'Torah: Hashem did what Moshe told Par'oh, even though he did not consult Him. 1
Oznayim la'Torah: Based on the Midrash that Moshe refused to take on the Sh'lichus until Hashem promised him that He would back him up on whatever he would do or say.
Why did the frogs that were in the ovens not die?
Da'as Zekenim, Moshav Zekenim and Hadar Zekenim (on Pasuk 7:28) and Ba'al ha'Turim (on Pasuk 1): As a reward for their Mesiras Nefesh to fulfill the will of Hashem by entering the hot ovens). 1