How can the Torah write "Va'avad'tem Sham Elohim"?
Rashi, Ramban #1, Rashbam (both citing Targum Onkelos) and Targum Yonasan: It is referring to being subservient to the idol-worshippers - which is considered as if one is subservient to the gods themselves.
Ramban #2: It hints that whoever lives in Chutz la'Aretz is under the jurisdiction of another god, 1 and it is therefore automatically considered as if he is worshipping idols.
Why does the Torah not add the word "Elohim Acherim", as it usually does when referring to idolatry?
Ba'al ha'Turim (citing Avodah Zarah 8a): This hints at the fact that Yisrael in Chutz la'Aretz serve idols be'Taharah (unaware that they are worhipping Avodah-Zarah). 1
Avodah Zarah 8a: E.g. a Nochri makes a feast in honor of his son's wedding, and invites all the Yisraelim. Even though they eat their own food and drink, and a Yisrael serves them, the Torah considers this an idolatrous feast - "v'Kora Lecha v'Achalta mi'Zivcho."
Why does the Torah see fit to list four senses (hearing, sight, taste and smell)?
Ramban #1: It mentions hearing and sight, to point out that the gods that they worship are not deities at all - since they do not see their troubles or listen to their prayers, and adds that they are devoid of even the most physical senses of taste and smell, thereby rendering them inferior to those who manufacture them, unchanged from the stones that they were before they were manufactured.
Ramban #2: In contrast to Hashem, their gods cannot see the troubles of their adherents or listen to their prayers, and that they are incapable of even emitting fire to consume the sacrifices that they place before them or to smell the fragrance of their offerings.
Seforno: The Torah is telling us here that the gods of the nations have no will of their own. 1
Riva: Eating and smelling refer to acceptance of Korbanos - "va'Tetzei Esh
Seforno: Despite the fact that those who manufacture them make them with the Keilim with which one expresses one's freewill (eyes, ears, a mouth and a nose), and worship them and pray to them in the hope that they will respond. In fact, the only creature that has freewill is man.
Why is there a 'Nun' at the end of "Yir'un, Yishme'un, Yochlun, Yerichun"?
Ha'Kesav veha'Kabalah: Meforshim say that they are extra. Really, the suffix 'Nun' is used when speaking to females
Why does the Torah list other senses, but omits speech?
Kol Eliyahu, Divrei Eliyahu: Shir ha'Shirim Rabah (1:9) and the Zohar bring an episode in which Nebuchadnetzar made a Tzelem and put the Kohen Gadol's Tzitz in its mouth, and it was saying Anochi Hashem Elokecha. Daniel ordered the Tzitz to leave; it left, and the Tzelem ceased talking. The Torah hints to this. The Tzelem lacked the other senses, but seemed to speak. Seek Hashem Elokecha