Feeding from 11-24 hunger gives the most bang for your food (1 loyalty point). Feeding from 25-75 is only 75% as effective, feeding from 1-10 is only 50% as effective and feeding at any other time even makes it lose loyalty. Also if it stays at 1 hunger it loses a loyalty point every 3 minutes.
As for making it autocast caprice, you'll have to read the manual that came with your AI.