To close all windows of the app, press Option-Command-W. To minimize all windows of the front app, press Option-Command-M. To view the front app but hide all other apps, press Option-Command-H. To find the previous occurrence, press Shift-Command-G.

Command-G: Find Again: Find the next occurrence of the item previously found.Command-F: Find items in a document or open a Find window.In some apps, you can undo and redo multiple commands.

You can then press Shift-Command-Z to Redo, reversing the undo command.