2. If Jesus included everyone in "anyone who partakes", then why did he institute the memorial with only his 11 apostles? Is there an indication that he invited everyone, and only his 11 apostles turned up?
Dw: Jesus, at that point had the right to everlasting life earth, which he was about to sacrifice. the 11 apostles had a firm hope of an earthly kingdom too, when jesus served the bread and wine to them. They would through that symbolism have the right to everlasting life on earth, forgiveness through the new covenant.
All partakers get the right to everlasting life on earth, not immortality in heaven, but not all are called to give that restored adamic (or Eve) perfection up in wt land, only 144 000 sealed once.
Jesus served the emblems to earthly hope "sheep". it behooves wt to do the same, to claim to be his followers.
sorry for split reply, got balled up in the premature yellow.