1) First point could be achieved using listShuttle. (toltip could be pointed to the components in columns) Unfortunatelly it not possible to attach it to select items.
2) grouping functionality isn't available with both listshuttle and pickList components.
So seems you need some custom facelets to achieve the functionality you need.
I have thought of a workout against this situation of grouped items. I am thinking of making the level 1 options unselectable in the pickList. I tried by setting the attribute disabled to true. But the items are still selectable. Is there any other solution for this?