Baptism by immersion is the mode used in the New Testament. Baptism commonly means to plunge or immerse in water. This is the commonly recognized meaning in ancient Greek and literature inside and outside the Bible i.e. Mark 1:5,10 etc. The symbolism of union with Christ in his death, burial, and resurrection seem to require baptism by immersion i.e. Rom. 6:3-4.
The outward symbol of beginning the Christian life should only be given to those who show evidence of having begun the Christian life (Gal 3:27). Baptism is not necessary for salvation but it is necessary if we are to be obedient to Christ. The age varies—they should be old enough to give a believable profession of faith.
Before and after 1 Cor. 11:23 Paul is highlighting not just the vertical nature between God and individuals but also the horizontal nature between individuals and the community. Followers of Jesus are bound into a new human fraternity—the church. In 1 Cor. 10:16-17 the focus of community being a major factor in the Lord’s Supper is key. It has supernatural roots derived from God’s love in Jesus.
This community life is exhibited and visibly depicted by the sharing of the emblems of the body of Jesus. Each communion celebration is a local expression of the universal church. The word “covenant” appears in all the accounts of the institution of the Supper. It is safe to say that the Lord’s Supper in one aspect is a covenant rite, a personal pledge of loyalty, a promise of straight dealing on God’s part with us, and our part with him awaiting his triumphant return.