Why does the Torah see fit to repeat that Noach did what HaSh-m told him ("Ken Asah")?
Rashi (initial text): To teach us that Noach neither added nor subtracted even one detail to (from) what HaSh-m instructed him.
Ramban: It is the way of the Torah to stress an achievement in this way.
What exactly does "all that HaSh-m told him" refer to?
Ramban: It refers to building the Ark and collecting and storing all the food.
QUESTIONS ON RASHI
Rashi writes: "'And Noach did...' - this refers to the construction of the Teivah." How does Rashi know this?
Gur Aryeh #1: If it meant entering the Teivah, then the verse below (Bereishis 7:5) would be superfluous.
Gur Aryeh #2: Noach was only commanded to enter the Teivah in the following verse (Bereishis 7:1).