How can I make the lister show file extensions, in addition to Name, Size, Type, etc. in all the folders? I know how to do it for an individual folder, but have not been able to set this a the default for all folders.
How, in one go, can I copy a file from a folder to itself, renaming it on the way, so I have the same file in the same folder under two different names?
Add the Extension column to the list. If you want to make it the default, choose Save For All Folders from the Folder Options dialog, or via Preferences edit the Custom item under Default Formats.
Use the Duplicate command, by default it is the right-mouse button action on the Rename button.