Top-right is (when applicable) the Variable Insert Button.
When editing certain action parameters, you can insert a variable by pressing this button and selecting the name of the variable.
Text parameters are sometimes optional: in that case the text Optional will appear as a hint unless the entry box has already been filled in.
Text parameters also sometimes have a dialog to help you fill in a value, in which case the text Long-Click will appear as a hint, unless the entry box has already been filled in. To access the dialog, you can long-click on the text entry box.
Please see the section on Flow Control for more information.
Bottom-centre, indicates whether the specified action is a setting or not. Please see here for more information.