The Item Abilities will be used to fight other opponents. When you attack someone the script randomizes your abilities (if you have more than 1, as some do), and shows the effects of that ability. They are worthless right now, but it'll add up in the end. Good observation.
Sounds good. I was thinking, not so much random movies, but you can only use certain moves a certain amount of times in battle (the more powerful ones can drain your "Magic" or something, or some can have recoil). I don't know, just a thought.
Oh, that's great! You could take it even farther by having some moves make you lose a next turn, or something. Drawbacks as well as benefits adds to more strategic combat.