What exactly is "Ashmores ha'Boker"?
Rashi: The night is divided into three watches (each comprising four hours), when three groups (Mishmaros) 1 of Mal'achei Shareis sing Shirah one after the other - and it was at the beginning of the morning watch - the final one, that Hashem began to switch from the salvation of Yisrael to the drowning of the Egyptians.
Which explains why the Torah uses the word "Ashmores" (and Onkelos - 'Matras' [Rashi]).
What are the connotations of the word "Va'yashkef"?
Why does the Torah again refer to the Pillars of Fire and of Cloud?
Rashi: Because they not worked in conjunction to create havoc among the Egyptians - The former turned the congealed water into mud and the latter then boiled the mud, and the boiling mud burned the hoofs off the horses' feet (causing them to go wild [and the wheels off the chariots, causing the chariots to drag, their riders being hurled around until their bones came apart]) 1 .
Targum Yonasan: The Pillar of Fire shot burning coals at the Egyptians, and the Pillar of Cloud, hail-stones.
See also commentaries on Pasuk 25.
What is the meaning of "Vayaham"?
Rashi #1: He confused them, causing them to lose their common sense. 1
Targum, Targum Onkelos and Targum Yonasan: Hashem caused them to go crazy.
Rashi #2 (citing Pirkei de'R. Eliezer ben R. Yosi ha'Gelili) and Rashbam: It means that He caused them to hear terrifying noises. 2
Hence, in Pasuk 27, the Pasuk describes how they ran towards the oncoming water instead of running away from it (See Rashi there [Refer also to 14:25:1:2).