Altium Designer, Shortcuts for Viewing, Changing Grid and Snap Setting

Toggle measurement Unit: Q
Accessing Grid menu: G
Changing snap setting: SHIFT + E
Switching 2D and 3D View: 2 & 3
Fit all objects into view: CTRL + PAGE DOWN
Zoom in around the cursor (zooms around the cursor, position the cursor first): CTRL + Mouse-wheel up (or PAGE UP)
Zoom out: CTRL + Mouse-wheel down (or PAGE DOWN)