Result

Windows

Mac OS

Select all objects on layer

Alt-click layer

Option-click layer

Copy selection to new layer

Alt-drag small square to new layer

Option-drag small square to new layer

Add new layer below selected layer

Ctrl-click Create New Layer

Command-click Create New Layer

Add new layer to the top of the layer list

Shift+Ctrl-click Create New Layer

Shift+Command-click Create New Layer

Add new layer to the top of the layer list and open New Layer dialog box

Shift+Alt+Ctrl-click Create New Layer

Cmd+Option+Shift-click Create New Layer

Add new layer and open New Layer dialog box

Alt-click Create New Layer

Option-click Create New Layer