1- Prophet Adam did not sin. You can see this video for an explanation:
2- This claim about Imam Ali (a) suggesting to the Prophet (s) to divorce her is narrated in Sunni sources. We don’t have an authentic hadith that states he did, so we cannot confirm he did. There is no evidence for it. Assuming he did, it’s not because Imam Ali (a) doubted her chastity. It was probably because this issue caused a major headache for the Prophet (s), and so the Imam suggested she gets divorced to put an end to the whole controversy. It does not negate his infallibility.
3- As for Prophet Yunus (a), he did not commit a sin by leaving his people. His people were acting in a very evil way and they deserved punishment. Yes, he should have been more patient with them, but by leaving them he did not do anything wrong. Scholars state prophets sometimes commit Tark al-Awla, which means they don’t choose the best choice. Sometimes you have two choices to make. Choosing any of them is not a sin but one is better than the other. Sometimes prophets would not choose the best option. But they are still infallible. They would not violate the law of God.