A few thoughts on the government system. I haven't formed the exact system yet, but it should all come down to something similar to the current neo-democracy. It is true that in this system the parties are divided much more strictly and much more separately - some of them are for example: Agriculture and Natural Resources Guild, Manufacturing Guild, Astronomer Guild, Defense and War Guild, Expansion, Business and Bureaucracy, Society, Diplomats, Religions and Supreme Guilds .
Each of them has a minimum population share of x% and has one vote on one or other aspect of the law. The Supreme Guild oversees order in all guilds and has three points. An adult (30 years of age or older) can belong to one of the guilds. Guild areas are designated by agreement between the guilds, following a proposal by the Supreme Guild or a referendum.
The internal system of the guilds is simple - the guilds have their respective governing bodies, presidents, councils and so on. Guilds are concerned only with their own area, but can overrule the decisions of other guilds if they conflict with the interests of that guild and if they get enough votes from other guilds.
The Supreme Guild keeps things in order, publishes and submits the proposals gathered in public referendums, and has various other unique powers to help decide the fate of the guilds. However, other guilds are always free to oppose the High Guild's decisions and ask the next referendum to put the question to the public.
At critical moments, the supreme authority assumes totalitarian power.
The Supreme Guild is made up of the best of the best of the various guilds, elected in equal parts, and the 50% Supreme Guild is made up of various citizens who do not belong to any guild.
The Supreme Guild may have a population of y%. The number of members of the remaining guilds is limited to y*3% inhabitants. Guilds other than the top guild are subject to various sanctions if they do not have the desired number of members, or if they merge with another guild of a similar nature.
Each guild can have its headquarters wherever it wants in the solar system, as long as contact with them is not lost, and must have representatives in the main city Z. [Capital, perhaps? Or maybe the diplomatic capital? I haven't thought of it yet, probably the latter]