The deal with Zero is: enjoy covert action and character interaction (we do) while absorbing the complicated background information as it is gradually revealed to us. This has to be a spoiler alert. If I am going to unravel this interesting futuristic scenario while still reading the book for the first time, then I will discuss details that others would prefer not to know until they have read the book to its conclusion. And I might get some of the details wrong but will then correct them later.
As far as I can discern so far:
there has been a "Whole World War" (p. 47) (thus, we might say, not a WWIII but a WWW);
there is an interplanetary civilization called the Orbit;
the Orbit defense/security/enforcement agency is called the Service;
the Service has Headquarters in Sydney and a Command Centre in space (this implies that the center of civilization moved to the Southern Hemisphere and/or off Earth after the WWW);
the Zero, ostensibly a "...a pirate ship..." (p. 47), is really a covert Service ship (does piracy work in space?);
Colonel Luscombe of the Service assigns the Zero to investigate "...Albion Integrated's revenue stream..." (p. 43) (will AI turn out to be run by an AI?);
the only way to access the relevant data is physically to burgle the AI command centre on Earth;
while doing this, the Zero commander casually kills an AI security guard.
Stop! Morality alert! Who are the good guys and who are the bad guys here? Is this "Service" really a Service or an instrument of oppression? That is all that I have got so far. Well, there has been a defeated Lunar Revolution as well but right now I am mainly concerned about the moral issue of our heroes (?) casually killing someone especially since they could presumably just have rendered the guy unconscious.
This has become my way of engaging with a text. It takes a while. But I get a lot more out of it than if I just read the text straight through.