You can create a secondary window by doing a shift left click & drag from corner of 3D View.
Under linux, window manager of OS allows user to precise to keep this window always on top the other windows.
Under Windows, somebody made an addon for that.
Workspace will be saved only for .blend file of session.
It should not be a problem.
But if you are scared of that, you can do a right click on Workspace name, duplicate workspace and only modify the copy.