These three terms refer to concepts developed respectively by Deleuze, Badiou and Meillassioux to describe the absolute productive principle of nature hidden underneath the world we can see and articulate.  It is important to grasp that they are basically talking about what Lao Tzu called Dao (and to resist the obscurantist asceticism that inspires many contemporary philosophers to foreclose the ancient/religious roots of these things).  Whatever it is - whether it is capable of contradiction or not, whether it it can be detected via inner intuition or not, whether concepts can capture it or whether they can onl be thought 'according to' it - it is basically a kind of monstrous and yet subtle creating and sustaining force that works underneath the laws of nature.   A thinker has to make a decision, it seems, about its relationship to mathematics, empirical science, and art - and then go from there. Or is there a way to know?  In any case, it is hard enough to even clearly recognize the nature of the question and establish its validity.  

Maybe metaphysic is fundamentally the question of the relationship between the infinite (defined potentially in terms of contemporary mathematics, but not necessarily) and the finite, the unlimited and the limit, the apeiron and the peras, the unseen and the seen.

Beyond metaphysics there is still always the question of cosmogony: the question of the one/real/wound that accounts for the apeiron/peras distinction in the first place.