We can also explain vs 16, that Yosef was lost on the way since he really didn't want to find his brother. Since he really did not want to face them, he didn't try especially hard to find them. When he describes what he is looking for he says "My brother do I seek." This could be interpreted as a plaintive yearning to reestablish closeness with his brothers. Thus he was conflicted between a desire for peace but fearing the confrontation needed. He was trying to avoid a situation rather than trying to solve it. This lead to his suffering from the unresolved hostility. It is always best to face hostility squarely and to deal with it. Avoidance will lead to more trouble.
A recurring theme runs through this and the accompanying stories, clothing. Jacob tricks his father by wearing his brother's clothing. And so Jacob is tricked by his sons in their bringing to him Yosef's blood stained coat. Jacob is forced to identify it as his son's, much as Isaac had to identify Jacob as Esau. Jacob suffers the same fate he inflicted on his father, misidentification. Both these misdoings come from the desire to get what one wants without suffering the concommitant downside. Jacob did not face his father head on and argue that he should get the blessings. He avoided this confrontation and gained the blessing surreptitiously. Similarly, the brothers were afraid to confront their father with their feeling and argue the sides. So they took the easy route and got what they wanted without a direct conflict, but at what cost? Tricking family members in this way will ultimately lead to greater tragedies that the one one is trying to avoid. It is better to have the argument, however difficult that may be, than to avoid it trough a trick.
We can also understand the insertion of the Yehuda and Tamar story in this same vein. Apart from it showing the downfall of Yehuda and his tshuva (and perhaps the misuse of yibum) it also shows us how Yehuda is willing to properly identify clothing. He identifies his staff and signant in the hand of Tamar even though this leads to his own disgrace. He has done teshuva and will correctly identify what is his. Yosef suffers the consequences of his clothing being properly identified as well, even though the crime he did not commit. His clothing in the hands of the wife of Potifar leads not only to his disgrace but to his imprisonment. But his willingness to admit to his supposed crime ultimately leads to his becoming viceroy of Egypt.
Both Yehuda and Yosef show their greatness by their willingness to accept responsibility. This itself is teshuva, admitting the truth instead of denying and avoiding reality. It is wearing the results of your actions instead of shirking them. If the shoe fits, wear it.
Compare story of Josef to Oedipus. Both achieve there destiny precisely by being prevented from it. Josef as the theological fatalist. As he says to his brothers, "It is not you who brought me to Egypt, but G-d who send me ahead to be the provider." Joseph attributes human free will actions to a Divine plan.
The brothers sale of Joseph as a slave for their own profit is a cold hearted addition to an entirely shocking set of events. Admittedly it is better than killing him, but shows a terrible flaw of character. Are they only interested in money when their brother is suffering so? And sitting down to eat bread while he cries and pleads with them to release him is particularly cruel. (We know from the brothers' later account in Pharaoh's court that they ignored Joseph's pleading.) It must be understood in two lights. First, it is typical of the cruelty that young boys, of about 12 years old, can inflict on each other. It is therefore easier to understand the story as about children who later come to regret their behavior. Children often lack the foresight to realize how they will feel later about what they do now. That is maturity. And this leads they to do all kinds of evils. Second, we need to view their actions in the light of their father's actions. When they sold Joseph they were concerned with "what profit would they see from it." (This is explained in the Haftara as the desire to use the money to buy shoes. The other connection to the Haftara is that it is written there that a father and son will go to the same woman. This is exactly what Judah did when he slept with Tamar, his son's wife.)
This need for money is really inherited from Jacob. Remember he wanted to get the double portion of the Bechor from Esau. When Esau sits down to eat, Jacob first gives him bread (as the Rabbis point out, so that when he will eat the lentils he will be already satisfied and not hungry so that he cannot claim afterward that the sale was a forced one (onnes) because he was dieing of hunger and therefore should be nullified.). This bread is the same bread the brothers sit to eat while Joseph is pleading with them from the pit. He also implemented various schemes to get sheep from Laban. And when he came back to the Land he risked his life for the last of his vessels (As Chazal point out, "A Zaddik's money is dearer to him than his life." And this can be explained in a good way, he earned his money unlike the rasha, and it represents his legitimate needs in serving G-d.) So the brothers behavior, however inappropriate needs to be seen as inherited behavior from their father.
Rabbi Uziel Milevsky z"l points out that the essential argument between Joseph and his brothers is has the work of refining the bad character traits out of the Jewish people been finished. A farmer who want to grow the best carrot will select the best carrot from his crop and plant next year's crop entirely from its seeds. He may repeat this process for several years until he has refined the carrot to be the best possible. In a similar way, the generations from Abraham to Jacob are a process of weeding out bad traits. Thus Ishmael and Esau have the bad traits of their parents and only Jacob is perfect. (As Chazal say, "His bed is perfect"). But Joseph felt that the refining process was not over. It still needed one more generation, and that was he. He felt the brothers were not really perfected. The brothers felt that they were all perfect now (If anyone was imperfect it was Joseph, so they felt. Just as Issac loved the evil son Esau, so Jacob was making the same mistake in loving Joseph)
The proof that Joseph is really right is that the brothers did still have a bad trait from Jacob, the preoccupation with personal monetary benefit as shown by Judah's proclaiming, what benefit will we receive from killing him, let us sell him. Even if Judah was saying this only to persuade his brothers, that fact that he thought it would work and it did in fact persuade them show that at least on their part they had inherited Jacob's concern for money.
Joseph on the other hand was the perfect leader. In our own experience, politicians invariably use their position for their own betterment. Not so with Joseph. He had two leadership roles before becoming Viceroy of Egypt. The first was as the manager of Potifar's house. The second was as the deputy warden in the prison. (These two role represent the two main fields a modern leader must be expert in: Economics and Security. Politicians either promise they will bring more jobs, lower taxes and a better economy or they promise more police, law and order and a powerful army. Joseph was trained in both these fields.) In both his jobs he was entrusted with complete power. Potifar gave Joseph total control even though he was a slave. Joseph never abused this trust, never used it to try to escape. And when he was presented with the choice of violating the trust or going to prison, he chose the latter. So too, as a prisoner he was made warden. Presumably he had the keys to the jail but he never tried to escape. He was the model of magnanimous trustee. He never sought his own financial gain or betterment. He was purified of his father's focus on money. And this ultimately made him a great leader, and this was recognized by all those he met in Egypt.