As you can see on the screenshot below there is only one row containing the buttons delete, clone etc. That's because you first need to click on the item you want to edit.
In this case I've clicked on the "nature" item. You could for example instead have clicked on the "toggle" item, or the whole white block which is an item as well.
Deletes the current item. Be aware! This can NOT be undone!
It will make a clone/copy of the current item including it's sub items and will place it directly after the original.
Sort down
In the screenshot, there is an arrow down. Clicking on it will make the item move one step down in the current level. On this item there is no arrow up because we are already on the first item.
Sort up
The arrow up will do the same thing but up one step and it will be shown on items that have at least one item above.
Drag & Drop
With the arrow move cross you can drag and drop an item to sort it. It's only possible to sort an item to other items within the same level.
The arrow down icon next to the "Add" button indicates that there are more than one fieldset. Clicking it will bring a dropdown list for you to select the fieldset you want.
The plus icon next to the "Add" button indicates that there is only one fieldset. Clicking it will add a new set with fields.