What happens when a priest stripped of his sacerdotal duties performs a baptism or any other holy mistery that requires a priest? Is the baptism (or other holy mistery) valid or not?
I've heard conflicting views about whether or not Baptism can be legitimately conveyed by a lay person or not.
Anything else cannot be done without a Priest though, I'm pretty sure. It will convey no redeeming effect.
So: is the holy mistery of the holy orders until death or it can be "revoked"?
The Mystery of Holy Orders can be until death or even perhaps unto eternity (this latter part is not at all dogmatic, I've just heard some speculation). But yes, it can most certainly be revoked by the authority of the Church to loose and bind