Answer 1

The button with a little box inside it is the colour picker element. The little box's colour changes to the colour selected from the colour picker dialog.

Use 'onchange' attribute rather than 'onmousedown'. This way, the body background colour will be updated using the selected colour.

And what was that border-radius thing about?

Answer 2

I don't know how, or even if it was possible. At best I guess, you can set border-radius for the <input> element itself.

Maybe someone knows how, just wait ...