1)
What is the meaning of "Yamushu"?
1.
Rashi: It is to cease, like "Lo Yamish" (Shemos 13:22).
2)
Will none of these Chukim cease?
1.
Radak: This refers to the sun, moon and stars, but not to splitting the water, which did not endure; the sea returned to its normal state. Just like these laws do not cease, Yisrael will not cease to be a nation in front of Me, i.e. constantly serving.
3)
Why does it say "mi'Lefanai"?
1.
Radak: I establish them in their laws.
2.
Malbim: Their choice to be a Kadosh nation in front of Me will not change.