In Catholicism, there is the view that in certain sacraments, a non-priest/bishop can be the minister. For example, deacons are able to baptize in ordinary circumstances, and laity and even non-Christians can baptize in emergency situations (i.e. imminent death). A deacon can also be the witness of matrimony, since the man and woman are the ministers. How does Orthodoxy view the ordinary ministers of the mysteries? Can a deacon baptize? Can lay or non-Christians baptize in extraordinary situations? I know that Eastern Christianity views Matrimony differently, as far as it is something conferred by the priest (right?).
Basically, who can and cannot celebrate the Mysteries of Orthodoxy?