Assuming future researchers are not zombies or cannibals I think the embalmed or otherwise impregnated with plastic etc. one would offer more useful info to future researchers than something where the internal cellular integrity has been sliced to pieces by ice crystals.
Doubtful, since we already have examples of both types of preservation (Mummies vs. The Iceman), and the frozen corpse was in much better condition.
And, at “absolute zero,” it would suffer no further damage other than the initial ice crystal damage.
Those are both very crude and not all that useful examples relative to modern preservation with infusion of plastic vs cryogenics. As to taking a biological sample down to near absolute zero I think there would be more problems cropping up with that method than just ice crystals to contend with.
The problem is that the objective of preservation isn’t very clear in this thread. Is it for display, for possible future revival, or for research, and if so, will that research be more interested in purity from contamination, or preservation of structure?
When human brains are preserved for research, I believe they freeze half and pickle the other half.