I'm working on my first mobile site and need to make an image pinch zoomable.

I read that including this meta tag will enable it:

<meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no;" />

My questions are:

Which of those attribute enables it?

With that meta tag, if I display an image, say 600 x 1000, on an iphone screen, will it just automatically scale down to fit the screen, and automatically be pinch zoomable?