Good questions, of course.
First, regarding scenarios, yes, the game is moddable -- something I will address in more detail at a later point. We certainly want to encourage modders. What you are seeing in the big map is the setup for the standard scenario, but we have others, and will have more. (A list is on the products page.) At release we will have 25 scenarios total, but plan to add more very soon after release, and will continue to add both historical and alternate-history scenarios.
As for the AI, it is loosely scripted. In general, and I will address this in more detail at a later point, scripting merely suggests to units where to head and whether to be defending, attacking or reinforcing, and the code then decides whether to go along with that or retask the units. So both the player and AI have a lot of free will.
< Message edited by Gil R. -- 3/26/2015 2:35:03 AM >