I am not confused about any of the issues you suggested - you are.  

As for the Seder Meal that information is literally from the Book of Exodus and if the Messiah didn't follow those instructions than that would have been proof, in Jesus' time, that he was not the real Messiah.  This is why he did follow these instructions perfectly.

Jesus was a Messiah from Judaism, not the Catholic interpretation of Judaism desperately trying to justify sexism.  Those men and women Israelites who did not eat and take full part of the sacrificial lamb at the first passover (which is what all future passover meals are based on and symbolize), they could not leave Egypt with the rest of the Israelites, per the directions given to Moses by God, to enter the promised land.  This is why every Seder Meal is a Family Meal and why the Last Supper would have been the same way.