These are the sorts of questions that I don't think need an answer for you to run your Psi-Wars game, but if we want to "internally model" what's going on, it might be useful for us. This post dives into economics, hyperspace geometry and the Pareto principle to give us an idea of what the Empire (albeit one using the compacted, manageable numbers I've stuck to throughout the design process) might really look like.
The Scale of the Empire is available for all $1+ patrons. Go and take a look! If you're not a patron, as usual, I'd love to have you!