Interface types

Working on a simple hidden object puzzle scene.
Got objects clickable, that disappear.
Have created a sam & max style inventory like window for the hidden object checklist.

1. Was going to put a semi transparent image over the top of the interface list.
Can I have different interfaces for different scenes - basically the same layout, just different semi-transparent image over the top for the hidden object checklist?

2. Should i be treating this as an inventory interface, or secondary, or what? I do want a deponia style inventory in the game also. Am going to use the Menu/Scene system for my in game ipad menu screens.

3. Can I get objects/inventory to go to specific slots? So I can have my semi transparent overlays...
Like can I set a condition that when the item is clicked, it appears in the correct location on the Hidden Object Checklist.
At the moment I have only set them up as scene objects and used conditions to make the disappear. Do I need to make them items, since I don't want them as actual inventory?