How many times is one ordained?

In all the brouhaha about the status of the SSPX bishops, I realize I am completely ignorant of Catholic sacramental theology pertaining to ordination as it applies to the episcopacy.
The consensus of seemingly knowledgeable people is that the 4 were validly but illicitly ordained bishops and therefore, they ARE bishops, since the bishop who consecrated them had the ability, though not the right, to do so. (I am reminded of an hysterical novel by A N Wilson, the title of which escapes me, that deals with a surfeit of preposterous bishops, valid, by Anglican lights, but illicit, wandering about England creating mischief and sowing confusion and continuing their valid but illicit lines of episcopal succession. But I digress.)

Now I understand the conversations about illicit but valid Masses, or, as in recent goings on in Australia, IIRC, baptisms that were invalid, (though, had proper form been used, they would have been valid.)

Is the consecration of a bishop not an "ordination"? is it a sacrament?
So ordination is not a sacrament that can only be received once, (patently, as one is "ordained" to the diaconate.)
If ordination leaves the "indelible mark" on a man when he becomes a priest, does consecration to the episcopacy just... leave a bigger mark?
A darker mark?

And since sacraments confer grace, irrespective of the virtue or sinfulness of the minister of that sacrament.... is Bsp Williamson due the deference bishops are? a shepherd with whom one may disagree but whose pronouncements are to be respected?

Are there some gaps in the logic of sacramental theology? There are certainly some gaps in my understanding of it, some trains of thought that have not yet been explored and definitively explained...