Why were the brothers jealous of Yosef?
Seforno: Because they attributed Yosef's newfound haughtiness to the rise in his father's esteem, which was why he dared say over the dream in his father's presence.
What does "ve'Aviv Shamar es ha'Davar" mean?
Rashi and Seforno: It means that Ya'akov kept the matter in mind (waiting for it to materialize). 1
Because he sensed that the dream was true.
Why does the Torah see fit to record that Ya'akov kept the thing in mind?
Rashbam: Because it explains why Ya'akov retained his faith in the correct interpretation of Yosef's dream, so that, when he received the wagons, sent on the express orders of the King of Egypt, he immediately understood that the dream had come true. 1
Rashbam: In spite of the fact that he had seen Yosef's blood-soaked robe, implying that he had been killed. See Rashbam..
Why didn't Ya'akov keep the first dream in mind?
Moshav Zekenim: Because it was specifically the second dream had to be from Hashem
When he lodged at Har ha'Moriyah on his way to Caran, he heard angels say 'Ki Ba ha'Shemesh'.
למה כאן כתוב "ויקנאו" ולא 'וישנאו אותו' כמו בפסוק ח'?
גור אריה (פסוק י'): בפעם הראשונה הם חשבו שהחלום הוא שקר, אבל כשחלם שנית הם הבינו שהחלום אמת ולכן קנאו בו.