From An Abstract To An Evil Choo-Choo, What A Step Down

I want to talk about the Galactus Engine. It's a giant thing, looks sort of like a train with centipede legs, has Galactus' skull on the front. It burst through the Fault from the Cancerverse at the end of Thanos Imperative #2, and it's been slugging it out with regular Galactus and all the other high-level cosmic "Abstracts" since then.

The Silver Surfer said it's the Galactus of the Cancerverse, weaponized, which I'm guessing means this was done to Galactus, rather than it's the form he naturally took in that universe. I'd also guess Mar-Vell was behind it, but why? I can understand trying to shut Galactus down. It's a universe where no one will ever die, so they'll need all the habitable space they can get. Galactus devours worlds, including ones people could live on. So they stop him from doing that. It might take some time, but he can't kill them, and eventually he'd exhaust his energies and be overwhelmed. It raises two questions for me, though:

1) Was Cancerverse Galactus offered immortality before he was weaponized, or no? I could see Galactus rejecting the offer, recognizing the fundamental wrongness of a universe without death. That's even though he's clearly a survivor. Survived the death of his universe, keeps on going no matter how little he may enjoy what he does to survive. Still, he's been portrayed as a fundamental power in the universe, one who bridges the gap between Eternity and Death, maintaining a balance between them. That could make him either too powerful, or too aware of the risks in the offer to accept. Or perhaps no offer was made at all. He may have been regarded as potentially useful, but too dangerous to extend the Many-Angled Ones' gifts to.

2) At any rate, now he's an engine. What's he running on? What's the engine providing power for? The engine probably provides power to destroy their enemies. As for what it runs on, I wonder if Galactus can draw energy from things that can't die? I don't believe the freedom from death extends to actual planets, but what of the people on them? Would their bodies resist being broken down into the energy he consumes, or would their consciousness persist even after they were turned into pure energy? Galactus tried eating the Elders of the Universe once, after they tried killing him. He ate them even though they couldn't die, but it didn't take, and they escaped, though Death erased some of them from existence.

But since the inhabitants of the Cancerverse can't die, could they serve as an eternal fuel source for the Galactus Engine? He breaks them down, and draws some energy from it, but they regenerate, so he breaks them down and draws energy from them again, going on forever. In the end, it's just adding a middleman, because I'm betting it's the Many-Angled Ones that empower the folks, so it's probably their energy the Engine would be running on.