Getting to them:
21. In giving communion the custom of placing the particle of consecrated bread on the tongue of the communicant is to be maintained because it is based on tradition of several centuries.
Episcopal conferences, however, may decree, their actions having been confirmed by the Apostolic See, that communion may also be given in their territories by placing the consecrated bread in the hands of the faithful, provided there is no danger of irreverence or false opinions about the eucharist entering the minds of the faithful. (CDWDS instruction Memoriale Domini)
The faithful should be instructed that Jesus Christ is Lord and Savior and that, present in the sacrament, he must be given the same worship and adoration which is to be given to God. (CDWDS instruction Immensae caritatis, 4.)
In either case, communion must be given by the competent minister, who shows the particle of consecrated bread to the communicant and gives it to him, saying, The body of Christ, to which the communicant replies Amen.
In the case of communion under the appearance of wine, the regulations of the instruction Sacramentali Communione of June 29; 1970, are to be followed exactly. (see no. 6)
22. Fragments which may remain after communion are to be reverently gathered and placed in a ciborium or in a vessel with water.
Likewise, if communion is given under the appearance of wine, the chalice or other vessel is to be washed with water. The water used for cleansing the vessels may be drunk or poured out in a suitable place.