What I've been looking into lately, a generic AI that could be adapted to any map, and easily changed to allow different personalities.
This would take a long time to code though -- It is possible though.
An AI that works in this manner would consist of a rough script that it follows, basically building up the base, making weapons, attacking, and if extra ore is available, expanding the base. Enemy actions would alter the string of events. For example it would have to judge which thing is the most important task to be doing (for example, if the enemy's building up a sizable force and it seems like it's going to attack, building a counter-force is more important than creating remote ore bases, or, in the case of a colony game, creating residences / managing morale).
As for random enemy attacks:
I've done some research into the Pinwheel. I haven't really posted much about it, but it basically involves sending different pre-set groups of units onto a map from the edge, waiting at a certain point for all the units to group together, then set off in unison to attack a specific point on a base. After the attack is finished (if the units win), they leave the map at a preset point.
Basically it's a 'set it and forget it' sort of thing. These traveling units have no home base, but just come off the map edges.
As for greenworld maps: Please read the wiki next time before posting -- it will answer a lot of your questions.
As for setting up the editor,
http://wiki.outpostuniverse.net/Making_Greenworld_MapsYou need the map editor version 2.1.2. (latest version)