Hellhounds are intelligent and gain speaking abilities once they're linked with a master (the Hellhound Master, in this case, or anyone corrupt and powerful enough).
From the codex: "Hellhounds also have the power to link their minds with a powerful corrupted individual, drawing on that individual’s mind to allow them to think, in exchange for absolute loyalty to their new “master”. The first power that a hellhound generally gains from such a link is the power to speak, and the sharper their master’s mind, the greater their own abilities become. [...] It is through these mental links that their minds become whole, and cease to be that of semi-conscious beasts."
As for the worms, they were treated as parasites. So... I can't see those "TONS" of zooerastia contents, At best, I can only think of the Wild Hunt's hounds, and that's because I haven't read the scenes in ages.
Also, just because something was in CoC doesn't mean it will or should be in CoCII.