“all his daughters.” The Bible only records Jacob having one natural daughter, Dinah, so it is likely that this refers to his son’s wives.
“I will go down to Sheol.” Jacob correctly understood that when he died he would be dead, not alive in heaven or anywhere else. Although some scholars think Jacob did not understand the afterlife and thought he would go to some kind of underworld place, there is no reason to assume that Jacob, who had personally met God, did not know the truth. It is Christian tradition that is wrong about the afterlife, not Jacob.
[For information on the dead being dead until the resurrection, see Appendix 4: “The Dead are Dead.” For more on “Sheol” referring to the state of being dead, see commentary on Rev. 20:13. For more on the resurrections, see commentary on Acts 24:15. For more on the soul not being immortal but dying when the person dies, see Appendix 7, “Usages of ‘Soul’”].