Are they controlled like a bee hive or do they have there own mind and work separately?
There is no hive mind, but they more work together like soldiers In a military. That is the general belief anyway, no evidence of a hive mind. There is a bit of instinctual stuff going on though.
Actually, since @Matthew is the one who does story, I would expect that kind of explanation to come from him. But they also said that they want to keep the mystery about the monsters, so I anticipate that we will likely never know.
That’s a shame. Hopefully we could find out ourselves in a future dlc or something like that.
which means we have yet to meet the general or commander. or the admiral. o.O