Judah, Joseph, and Jacob's birthright

Jacob had twelve sons, the firstborn of whom was Reuben. Yet, the birthright that should have passed on to Reuben did not due to Reuben's sin against his father (1 Chronicles 5:1-2). Naturally, one would assume that the next in line would be Simeon, the second-oldest. It did not pass to Simeon either. In fact, Jacob passes over all of his sons until he gets to Joseph. Now, he essentially passes on the birthright and blessing to Ephraim, the younger of Joseph's sons. I have a few questions regarding this. First, why does Jacob pass the birthright to Joseph's sons, and not Joseph himself? In fact, before doing so, why does Jacob essentially say that Joseph's sons are now considered to be his sons? What is the meaning of this? Second, what is the significance of choosing Ephraim, the younger, over Manasseh, the older? Finally, even though Ephraim has the birthright, the lineage of Jesus comes through Judah. Why then, does the birthright not pass to Judah? Why is there a disconnect between this birthright and the importance of Judah in Jesus' lineage?