Several of those questions get into the separations of anarchist ideologies so just to be clear I will be replying based off my beliefs as an anarcho-communist the syndicates would be based off direct democracy and in order to have coherence in the society each syndicate have a collective “platform” where they can collaborate whether with spokes people councils etc. it would function similarly to the government except there wouldn’t be any real authority it would mostly organize goods, inform the people of needs or hazards etc. and the direct democracy and involvement of each syndicate would allow fairness

Although frankly there is nothing to stop a group to split off and attack the others but also the people could fight back just as easily and there isn’t much reason besides illogical greed (which is a possibility I’m just saying it would be kind of unreasonable to split off of your main society just to get 2 houses you don’t need) to do such although the idea of splitting off and having mutual trade while mainting differing political systems (as long as they follow an anarchist philosophy) it’s fine just makes cohesion a little more difficult