Scras, the wording you used made me think you were asking about doing a campaign on CE instead of publishing CE as a novel which I thought was what you are heading towards. But then you talked about the first step towards publishing which I'm unclear as to what exactly it is: are you publishing a game manual based on CE? But then you said game mechanics aside so with no idea on what exactly you have in mind to do, not sure my response will actually be useful and relevant to what you're asking. But here it is regardless, assuming that you are asking about a CE novel and what meta world fluff I would like to see as a reader:
First, I love the presence of fluff in novels (specifically for fantasy, you know I stay away from sci-fis), they make me think that a novel has an underlying world that is vast and my imagination can run wild in it. For CE specifically, must-haves are the alternative history stuff that bring the society to where it is nowadays, the different eras gone through, the emergence of the different alliances, that kind of thing. And in what way the whole society is different from modern society now. Since this is a sci-fi, I presume you can throw in some awesome techs that you've written up, all the different types of virtual entertainment and different robots/cyborgs.
If you need a more specific response than that, then sorry, you need to specify in more clear terms what's this first step you are taking. And also, I'm probably not the best person to give advice since I'm still a very green player and don't even read sci-fi. Much as I admire your writing style in general, I've still not become an avid reader of CE after that taste of it I got from the RVE.