This is a thread about ZC Launcher - a program bundled with ZC which helps load it up with what screen size you want and things - not ZC itself.
If you want a script for an 'NPC follower' then there's the Scripting Forums, where you can request one or check the database for one...
..or if you want to see one in action, you could play my demo of The Legend of Zelda: A Key to the Heavens, which has one implemented ;-)
Not quite in the same way you suggested, but the idea of giving the friend a personality because Link can't have one's there.
Using each screen's palette on the map isn't an option, due to the ZC's colour restrictions.
However, in the betas there is a DMap flag next to the 'allow spacebar map...' one which says something like '...but only show screens on this DMap'.