1. The Midrash writes that Ya'akov should have been brought down to Egypt in chains, but Hashem didn't want to do that to him; therefore he caused Yosef to be brought to Egypt in advance and Yaakov then went willingly, to meet his long lost son.
What did Ya'akov do to deserve to be brought in chains? Why did he deserve that punishment?
Like we saw last week, sometimes what looks like a bug is really a feature. Sefas Emes explains that the holiness of Ya'akov was so great that it could not be contained or be placed in a spot like Egypt. It would be like trying to connect the wiring in your house directly to the power station -- you would blow up the entire house. You need transformers to reduce the power step by step along the way so that it can be contained. This is the chains that the Midrash is referring to -- "transformers" that would modulate the holiness of Ya'akov step by step. But that's not how it happened. Thanks to Yosef being there, Ya'akov was able to come into Egypt in one step. The kedusha of Ya'akov was able to be preserved in full force even in the darkness of galus.
2. Yehudah's plea for mercy for Binyamin culminates with his telling Yosef, "How can I possibly return without the lad [Binyamin] and have to witness the pain of my father?" (44:34) Similarly, earlier in his speech, Yehudah says that "nafsho keshurah b'nafsho," his father's soul was bound up with Binyamin's; Ya'akov was liable to die should he lose Binyamin. It is Ya'akov's pain which is the focal point of Yehudah's entreaties.
Two weeks ago I quoted from Chazal that Yehudah was punished for putting his olam ha'ba on the line should he fail to bring Binyamin home. Even saying such a thing with conditions attached is deadly serious! It was only Moshe Rabeinu's tefilos on Yehudah's behalf that undid the decree. So why does Yehudah barely mention this in his plea? Why does he bring it up only in passing, as a justification why he more than any other brother was doing the talking (Rashi 44:32)? You would think the potential loss of his own olam ha'ba would be of central concern to Yehudah.
Had you asked me I would have said that maybe Yehudah, thinking he was addressing an Egyptian viceroy, might have figured that the loss of olam ha'ba would not have made much of an impression on an Egyptian. The truth though is that Egyptian culture was very much concerned with the fate of souls after death. They may not have known what olam ha'ba is, but the concept would not have been completely foreign.
The Sefas Emes (5640) answers that this missing argument of Yehudah's -- what he failed to say more than what he did say -- is what caused Yosef to reveal himself. Years ago these same shevatim had seen Yosef as a threat to themselves, and they acted to preserve their own standing at the expense of their father's pain. Now, Yehudah was concerned only for his father's pain, ignoring his personal concerns. If Yehudah could put aside his personal plight and focus only on the needs of his father, was it too much to ask the Viceroy to do the same and put aside his own claims to Binyamin for the sake of another's welfare? These are shevatim who have been cured of their past sin.