Since angular momentum caused by the collapse of the black hole causes the spin, if the spin is finite, the collapse must also be finite (I.e. - it cannot collapse into a singularity). But how far can it collapse and how fast can it spin? If the spin were fast enough that centripetal force overcame gravity, it would shed mass until spin and gravity were in balance.Do you have a reference? I've not heard of that being observed; the simple answer would be no, not as far as we know; we know it's maximum speed, and all those BHs seems stable.
The event horizon is not the star. The star is long gone either as the singularity or close (a Torus maybe). Between the two - -star and event horizon - is time ( This is a conventional theory that I disagree with but that's another story). All time points toward the singularity.Since angular momentum caused by the collapse of the black hole causes the spin, if the spin is finite, the collapse must also be finite (I.e. - it cannot collapse into a singularity). But how far can it collapse and how fast can it spin? If the spin were fast enough that centripetal force overcame gravity, it would shed mass until spin and gravity were in balance.