When Selendis attacked Heaven in WoL she used Nerazim units. So, I don’t see why she cannot use them now.
One word. Lazyness. Just see the portrait for Xel’Naga Enforces and Xel’Naga Ambusher. Have NOTHING to do with the actual units. Or a lot of Ihan-rii structures. Are just recolors. Or the Cerberus portraits. They are not HD portraits like others, are just the unit model with a background, just the Larva Cerberus portrait have an HD model.
If you check during the campaign for the things that Swann send to you, the faction of them are stated to be “Swann’s Armory” so… Swann have his own faction, even if that is more likely a “sub-faction” that Swann use to test veichles ecc…
Nope, in the Evolutionary mission is quite clear the Zergs used are not the same of the Kerrigan’s Brood since during dialogue is quite clear Kerrigan is not aware of what that Zergs are doing in that planets and that Abathur send them to make experiments and create new strains. So, Abathur have his own Brood, probably the smaller Brood of the Swarm, but still, his Brood.