Sounds cool! It may be easier to make a mod that gives you the id and name of an item if a player interacts with the item. There is a player interact event.
Other events you can use: http://forum.learntomod.com/t/player-events-not-included-in-the-event-blocks/3055/3
It's not possible to make or use gui on learntomod. We did have a demo at one point, but it's not a feature that Development decided to implement after all.
But you can use our texture editor to make some items look different.