Alt+click in a panel using the main FigureJ tool logs the panel properties to the log window.
Alt+click on the 'draw label' button of the options window resets the label counter (it restarts from A.)
If you want to include panel content larger than your original file, you can adjust it's canvas size.
Use the 'Copy' and 'Paste' buttons to add a different view of the same image to a different panel
With panels of the same size, use the Alt+'Copy' and Alt+'Paste' buttons to select a new source image, but using the same ROI geometry.
After adding overlay elements with the 'options' panel, or with standard ImageJ commands, you can still move them, or change their properties (e.g. color or line width) by long-clicking them. Long clicking changes the state of an overlay element to active region of interest.