So... something I never really understood: the Masterpiece has Li'l Cal ending up in the Void, but how does Lord English actually come about from that? Maybe I missed something, but how does he end up bursting out of Doc Scratch if his soul is still floating around somewhere in the Void?

Doc Scratch was Alchemized from Lil Cal. The Lil Cal Hovering in the Void is basically a ‘Door’ for his Soul to Manifest within Lil Cal in other Universes. He tells us quite literally, he persists as a Nightmare- It almost feels like a disease, spreading through the Universe, taking control of people, hijacking First Guardians, anything in order to perpetuate himself and cause chaos and mayhem.