Why does the list the sun, the moon and stars separately - after "Vayishtachu lahem"?
Seforno: Because, as opposed to "Elohim Ahcerim", which refers to the spiritual angels, they are physical beings.
What is the meaning of "Asher Lo Tzivisi"?
Rashi and Rashbam: 'Which I did not command to worship'.
Why does the Torah find it necessary to add that Hashem did not command us to serve Avodah-Zarah? Is it not obvious?
Rabeinu Bachye #1: We might otherwise have thought that it is someone who pays homage to a servant of the king will find favor with the king.
Rabeinu Bachye #2: It is as if the Torah had written "asher Tzivisi be'Lo" - that Hashem commanded us with a Lo Saseh not to worship.
Rabeinu Bachye #3 (according to Kabalah): Although Hashem commanded us to bring the Korban Tamid "One lamb in the morning and a second lamb in the afternoon" 1 corresponding to the Midas ha'Tom and the Midas ha'Laylah, respectively, He did not command us to worship the sin and the moon.