Many philosophers have written about nothingness, see Nothingness.
Best known for this subject is Heidegger in his book "Being and Time" (German original: Sein und Zeit). The German term for the nothingness is “das Nichts”.
The lingustic problem with the term nothingsness is that the term reifies the negation. To negate a statement does not create a new noun. And because there is no new noun, one cannot ask for properties of the noun nothingness.
Therefore the main criticism of using the term nothingness is its tendency to create philosophical pseudo-problems.
Quantum fluctuations are a physical – not a philosophical – concept, see Quantum fuctuations. Quantum fluctuations are the spontaneous creation and annihilation of particles from the vacuum. I assume that’s what Krauss’ book speaks about.
Quantum fluctuations play an important role in quantum field theory. They are considered the seed of thefor structure formation in cosmology during the early time of our cosmos. See Alan Guth Inflation and the New Era of High-Precision Cosmology.