To minimise all windows of the front app, press Option-Command-M. Command-M: Minimise the front window to the Dock.
To view the front app but hide all other apps, press Option-Command-H. To find the previous occurrence, press Shift-Command-G. In some apps, you can undo and redo multiple commands. You can then press Shift-Command-Z to Redo, reversing the undo command.
