1) When I drag a file WITHIN the local panel and drop it in the local panel. WinSCP creates a copy of the file in the local directory. Is this a special feature? I think it may be better if this operation does nothing. Copying the file within the local directory is not intuitive to me. What do you think?
Left panel imitates behavior of Windows Explorer. And WE does duplicate the file when dropped to the same folder.
2) When I drag a file from remote panel onto an executable file in the local panel, the executable is run to open the remote file. Is this a feature? Can I disable it? I just want the remote file to be copied regardless whether I drop it onto an executable or onto some blank space in the local panel.
Option to disable this is on the wishlist already. I'll try to add it soon.
3) I noticed that there is an option in preference "Allow moving from remote directory to other applications". What does it do?
It allows you to use drag&drop to move files in addition to copy/duplicate them. However it has several drawbacks, so it is disabled by default.