Was Yosef allowed to hear his brothers call Yaakov "Avdecha Avinu," and not protest?
Sotah13b: No! 1 (Indeed, that is why he was called "Atzamos" (50:25) in his lifetime. 2 ) Some say that due to this, he lost 10 years from his life, or fathered 10 less sons than he should have (refer to 50:25:151:1 and 50:25:151:2, and the notes there).
Maharal (Chidushei Agados Vol. 2, to Sotah 13b): Yosef should have been bothered by this. Because he was honored so much, he was not sensitive enough to others' honor, even his father's. 3
Ramban (to 42:9): His efforts to fulfill his dream justified paining his father (refer to 42:9:4:1 and the note there). (How could he protest without revealing who he is?! He could have said, 'if your father is alive, why can I not see him via Nichush? It must be, he is a much bigger Tzadik than I - if so, do not call him my servant!' - PF)
A derogatory title for a Tzadik. See Torah Temimah, note 8. See also Torah Temimah to 50:25, note 22.
I.e. even if he was correct not to voice his objection, lest it impede fulfillment of his latter dream, he should have been pained to hear this. (PF)
Why did they bow?
Ha'amek Davar #1: It is because Yosef befriended them, and was concerned for their father's life.
Ha'amek Davar #2: They bowed on behalf of their father. This fulfilled the second dream, in which the sun 1 bowed.
This would be a better than fulfillment if they bowed also on behalf of Yaakov's wife - but we do not find that Yaakov's wife spoke to them about this, nor that Yosef asked about her, or even that she was alive at the time! (PF)
QUESTIONS ON RASHI
Rashi writes: "'They prostrated themselves' - [in appreciation] for the questions of greeting." What is Rashi clarifying?
Gur Aryeh: We cannot say that they bowed merely to honor the viceroy; as they had already done so (in 43:26)! Rather, they bowed again now for an additional reason - for he had inquired about Yaakov's welfare.