1) Is it possible to add completely new UI through a mod? (Say, a new button on the global interface, which brings up a brand new window, which offers some new options)?

2) If a button on the global interface isn't possible, can I at least create the new button on a unit's action bar, and have that bring up a new window?

3) How much customization of the AI is possible? Can I actually write code in a flexible language similar to lua or C#, or am I limited to basic triggers and formulas?

Basically, I'm thinking of creating more detailed customization possibilities to the basic unit AI to reduce micromanagement, and then adding preferences to customize the behavior you prefer. Is such a thing possible?