1. That just works. Check ui demo 5 - The function that adds stuff into a layout is in tk2dUIDemo5Controller.AddSomeItemsAuto, the relevant function is - "autoScrollableArea.ContentLayoutContainer.AddLayoutAtIndex" which adds an item. Similarly there is a RemoveLayout which removes an item from a layout, but you are still responsible for deleting the game object.
2. There isn't, after removing an item, you can force scroll to the centre of the scrollable area.