Buy workshops; Support town owner clan; You can't remove them definitely, the game will create a new one the next day in case they die or disappear (if really low power). They get power through the workshop and common areas they own and when supportive of current town owner. More power means higher level of troops to recruit.
There's 3 workshop per city. Through the encyclopedia tab (cities) you can see what type of workshop is in there (hover over the notables). Don't go for smiths, it makes crap money. Go for breweries instead. Save loads and loads on money, then buy every brewery in the world, change their type and sell it back (AI can't change a workshop's type).
Antaeus. I'm fairly sure you lose them. I'm not sure at what triggers them to be requisitioned, but they are. In the trade perk tree there is a 5000D insurance policy. You can choose to apply it to either workshops or caravans. I prefer to apply it to caravans because I lose far more of them over the course of the game.
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