Select a Layer: V
Zoom Tool: Z
Text tool: T
Crop tool: C
Toggle Grid System: CTRL + ;

eyedropper/ color selector : i
Ruler: i
you can shift tool in a menu with shift button.

How to Select and extract out the Image:

1- select layer tool by pressing v button from your keyboard.
2- press and hold the shift button and click on the icon of the layer, it will select the image.
3- Press CTRL + C for copy that image
4- Press CTRL + N for a new file of photoshop
5- Press CTRL + V for a paste that selected Image
6- Press CTRL + SHIFT + ALT + S to save that image for web.