This page contains my rationals for various decisions I made while creating GURPS/Snowcrash. By reading it you can learn why I did what I did.
When I started this project, I assumed that I would start with GURPS/Cyberpunk and then build Snowcrash on top of it. But the more I looked at GURPS/Cyberpunk, the less I saw which made sense in the Snowcrash world.
Whenever I wanted to ad a special ability, there were two ways to do it, modify the "unusual background" advantage or create a new advantage. I have created new advantages. I didn't see any real difference between the two, and I think they should be advantages on the same basis as any other advantage.
I have generally reused skills that already exist, rather than creating new ones. For example, administration is used in place of a new "franchise operations" skill. There is no new "metaverse" skill, instead there is programming.
I don't recommend buying Cyberworld, just to play Snowcrash. It is an awful world book, and not Cyberpunk. You can ignore it entirely if you want, or just copy pages 22-23 (which are useful), and pages 18-21 (which are slightly useful). Cyberpunk 2020 (from R. Talsorian) makes a much better "pure" Cyberpunk world book. But that is just my personal opinion. I challenge you to read any major Cyberpunk work, and find anything remotely like Cyberworld. The drawing are cool, though.
I had orginally wanted to put character creation rules first, then world descriptions, equipment descriptions, etc. But I looked through several GURPS suppliments, and they all had the world descriptions first, then the character creation rules, so I did it that way.