There is a crafting system similar to FarCry 3's. Kenway also has a fleet that you can deploy similarly to the way assassin's were deployed in ACB, ACR, and AC3 in order to obtain money, goods, and special items.
im at sequence 8 or 9 and as far as i see its far from as in depth as it was in 3. you can upgrade a few things for your self and your ship other than that you can buy buildings in your hideout for small bonuses like a brothel makes it free to hire "dancers". and you can send out fleets you capture to trade misc items you collect during your pirate raids, but you have to keep the paths clear using a sort of battle mini game. other than that it doesnt look like there is to much control over your area so to speak.