Having already related the dream to his brothers, why does the Torah repeat "to his brothers" again?
Rashi: Because, after telling his brothers about it, he related it to his father in front of them. Ha'amek Davar - He did not ask them, for they would not want to hear it. They did not interpret it, so that it would not be fulfilled. So he told it again, also in front of his father, who interpreted it. 1
Both his brothers and Yaakov asked incredulously about the apparent interpretation. Why does Ha'amek Davar say that Yaakov interpreted it, but the brothers did not? Perhaps Yaakov intended to interpret it; he asked incredulously to dispel the brothers' jealousy (refer to 37:10:3:2 and 37:10:2.2:1 - PF)
Why did Yosef not also relate the first dream to his father?
Ramban: Because he himself understood the obvious interpretation of the dream.
Sifsei Chachamim (citing the Maharshal): Because his brothers had already interpreted it for the good. 1
Hadar Zekenim: Yosef understood that only this dream applied to his father.
And he knew that a dream takes effect according to its interpretation.
Why did Yaakov dismiss the (second) dream out of hand?
Ohr ha'Chayim: Bnei Yaakov would not get greatness via the other nations, only via their father - if so, it is not feasible that Yaakov would bow to him. He said so to dispel the brothers' envy.
Rashi #2 and Ramban #1: He knew every dream contains some nonsense. 1 He dismissed it due to the fact that Rachel was no longer alive, 2 only in order to prevent the brothers from becoming jealous. 3
Rashbam: 'Do you think that I, your mother and your brothers will bow to you?! 4 - Even if Rachel were alive, it would be most unlikely. 5
Ramban #2 and Seforno: He thought that the dream was a sign of Yosef's haughty intentions to rule over his family, and he was merely 'carrying his thoughts on to his bed.' 6
Malbim: Yaakov wanted to interpret his dream favorably, but also avoid envy of the brothers.
Which the Gemara in Berachos 55a learns from here.
Rashi: He did not know that the moon referred to Bilhah, who raised Yosef as a step-mother.
Moshav Zekenim: Since a dream is fulfilled according to its interpretation, why is this incredulous? First Yosef told Yaakov, and Yaakov interpreted it, and then he said so to the brothers to prevent envy.
Malbim: A father does not bow to his son. Also your brothers, who are more numerous and mightier than you, will they bow to you?!
Ramban: As in Daniel 2:29.
Who did the sun and moon represent, who were destined to bow down to Yosef?
Rashi: The sun represented Yaakov. The moon really referred to Bilhah, 1 who raised him after Rachel died (but Yaakov did not realize this).
Ramban: The sun represented Yaakov. The moon represented all the seventy members of his household. (There were also eleven stars, for Yosef's eleven brothers bowed down to him before Yaakov and the rest of the family arrived.)
Da'as Zekenim (to 37:9): When Yehoshua told the sun to stand still, it did not want to. He told it, you already bowed to my ancestor!
The Ramban however, maintains that Bilhah and Zilpah died before Yaakov and his family went down to Egypt, in which case the moon could not have referred to her either.
What is the exact meaning of 'Hishtachava'ah'?
Berachos 34b: It means to prostrate oneself on the ground, hands and feet outstretched. 1
Berachos 34b: Which we learn from the fact that the Torah here adds the word "Artzah."
QUESTIONS ON RASHI
Rashi writes: "He told it to his father and his brothers - ... i.e. [he told] his father in [his brothers'] presence." Why explain this way?
Gur Aryeh: The preceding Pasuk (37:9) already said that "he told it to his brothers." It repeats it here to inform us that he told his brothers a second time - this time while in their father Yaakov's presence.
Rashi writes: "After he had told his brothers, he told it again to his father in [his brothers'] presence." Why did Yosef do this?
Gur Aryeh: Yosef wanted the brothers to respond incredulously to the second dream, as they had to the first - "Would you reign or rule over us?!" (37:8). By doing so, they would in fact be ratifying that this was the correct interpretation of the dream! However, the first time, the brothers deemed his dream insignificant or false, and responded. Now, upon the second dream, they realized it may be true; and they remained silent, not wishing to voice its interpretation. Yosef therefore went before Yaakov, hoping that he would interpret the dream as it related to the brothers as well - and in fact he did. 1
Gur Aryeh: This explains why the brothers' hatred turned to "jealousy" (37:11). See Gur Aryeh further.
Rashi writes: "[Yaakov] rebuked him - for he was bringing hatred upon himself." Why doesn't Rashi explain simply, that Yaakov's rebuke was because he did not believe the dream to be true?
Gur Aryeh: The next verse says, "His father awaited [the fulfillment of] the matter" (37:11). If so, Yaakov did believe that the message of the dream was true.
Rashi writes: "'Will we come?' - But your mother [Rachel] is already dead!" How do we know this was what Yaakov meant?
Gur Aryeh: Otherwise, why was Yaakov incredulous? (He was not responding, as the brothers had, as incredulous that Yosef would even imagine such a thing.)
Rashi writes: "Yaakov did not know that it was referring to Bilhah." But perhaps Yaakov did realize this; and he merely said this so that the brothers would not be jealous?
Gur Aryeh: Had Yaakov realized this interpretation, he would have had to suspect that the brothers realized it as well. If so, he would only have been fanning the flames of their jealousy, by implying that the dream would be true if not for this problem (that Rachel was no longer living). Rather, he failed to realize that it meant Bilhah.
Rashi writes: "Our Rabbis derive from here, the rule that every dream has void elements. But Yaakov's intent was to get [the dream] out of his sons' minds, so that they would not be jealous... He said, '... so too, the rest of it is nonsense.'" But perhaps Yaakov did not know the rule (just as he did not know the meaning of the moon - and he really meant this objection to the truth of the dream)?
Gur Aryeh: While it is true that according to Rashi, Yaakov did not know that the moon in the dream was referring to Bilhah (refer to 37:10:4.2:1); that is a matter of interpretation, which the brothers could have realized as well. But a rule can only be learned from one's teachers. Yaakov did not just 'know' it; rather he had learned it from the Yeshivah of Shem and Ever. He knew that he had not transmitted this learning to his sons; 1 there was no way they could have known this rule (that one nonsensical element in a dream actually shows that it is true).
Gur Aryeh: For Yaakov transmitted what he learned at Shem v'Ever, his primary wisdom, to Yosef specifically (Rashi to 37:3).
