You should be able to copy a panel dropdown from one panel to another by simply dragging and dropping it to the other panel dropzone (or duplicating the panel). We do have a small bug which we are going to fix which won't let you drag-and-drop a panel dropdown to another dropzone is "no filter" is selected. But you can workaround this by selecting something else first (in the meantime).
You currently can't re-order items in the panel dropdowns, but we are considering this for a future release (they just stay in the order you drag-and-drop them in).
