Yes but if these particles are only a couple of orders of magnitude down from a proton in terms of mass, the energy needed to create matter/anti-matter pairs would be much greater then that needed to create matter/anti-matter pairs of electrons.
OTOH, if instead dark matter is commonly distributed with anti-dark matter, the annhiliations that would be regularly produced should be easily observable.
Yes but if these particles are only a couple of orders of magnitude down from a proton in terms of mass, the energy needed to create matter/anti-matter pairs would be much greater then that needed to create matter/anti-matter pairs of electrons.That's true, but we can see evidence of distant anti-muon production and even anti-proton production, so such energies are available. (The mass of a muon is of the same order of magnitude as this supposed dark matter particle.)
OTOH, if instead dark matter is commonly distributed with anti-dark matter, the annhiliations that would be regularly produced should be easily observable.
That depends on how strongly coupled it is to electromagnetic particles like electrons. If the coupling is small enough, there could be a fantastic holocaust of annihilation occurring all about you--even through you--and you'd never know it.