I read a few months ago that a lot of DC and Marvel artists are jumping ship and creating a subscription-based comic site. Similar to you, they are designing the entire galaxy up from scratch, with each world having unique religions and governments. My own comic process is nothing like that. Since I write a comedy series I don't spend much time on world-building, and let the audience just assume "that city is like Metropolis" or "he's like Spider-Man." Saves me time borrowing from collective knowledge.

I have done world-building in the past, mostly for role-playing games. But I will usually start small and expose the world gradually. As 1st-level scrubs all they need to know is their town and the local threats. As they journey, then they become immersed in kingdom politics, continental threats, then sometimes extra-planar politics and governments. All that gets developed along the way. All that I come up with at the start is two things: 1) Who/what is the major campaign threat? and 2) An explosive start to the campaign. Aside from that I only have a vague idea of the path from beginning to end. Not sure if that's helpful at all, just want to reiterate, don't get paralyzed by perfectionism. You don't need all the small questions and details answered before you start, just the ones that will affect your characters right now.

Good luck. !BEER