Seeing as 'Kemach' is coarse flour, and 'Soles' is fine wheat-flour, how will we explain the apparent contradiction?
Rashi: The 'Soles' was in order to prepare cakes, and the 'Kemach' for cooking starch to seal the pots and absorb the froth. 1
Ramban: Avraham took three Sa'ah of Kemach, which he ground a number of times, until he had sufficient fine flour to make bread for his guests.
Hadar Zekenim, based on Bava Metzia 87a: First, he said "Kemach" (he thought that it is obvious that he intends for Soles). Sarah asked if she should use coarse flour, so he needed to explicitly say "Soles." This shows that Sarah was stingy.
Gur Aryeh: Why can we not interpret it as one phrase? It cannot be read as "Kemach of Soles," for Soles is not refined into Kemach, but rather the reverse. They must be two separate items, each of which had a different function.
Why did Avraham do everything in a hurry?
Oznayim la?Torah: Because it was Erev Pesach, 1 and it was already after midday, and P?lag ha?Minchah ? when it becomes forbidden qto eat even Matzah Ashirah.
Because he always served Hashem with Zerizus (alacrity).
Which explains why he told Sarah to prepare cakes (Matzah Ashirah), whereas Lot served the Mal?achim Matzos. See Oznayim la?Torah who elaborates in detail.
Why did Avraham tell Sarah to hurry?
Hadar Zekenim: Women are lazy.
