Deepnight Revelation - The Biologicals

So I'm introducing some of Deepnight Revelation into my Milieu 0 campaign, and one of the aspects is the biologicals. However I'm not getting a full sense of how to run them and how they operate. So I'm starting a few questions here and am interested in hearing from others.

So only actual braincases are technically "intelligent", for what that means for them. Braincases can directly control, but how much?

For instance in your first meeting with the Biologicals on Wildwood they know the characters are there just because they're integrated with the local flora or is it just that they've grown their own life among the flora that they control?

Is the central braincase actually controlling the early warning and defences on the outskirts of their area, or is it some very low plant/animal instinct that causes the seed pods and spines to attack the players?

I can't get a feel for how many braincases are in Wildwood, I'm actually thinking only the one main buried case. So this raises more questions, if there are no braincases in the Ambulators then just how much less instinctive are they? I'm not really seeing much that tells me a difference between something the biologicals have just grown and exists, and what is currently being operated by braincases.

On a complete side note, the Biologicals would be a great case for having a flowchart decision tree on how to respond to situations.