So, you just run a sling through your main hook on the crane, attach two hooks or shackles to both ends, and attach your load slings to the hooks or shackles. And when the piece is picked, it will balance itself out equally, more or less.
Yes as long as the strap thru the hook is close to its position. It is easily adjustable with the use of various length straps. A longer strap would give better load angles at the pick point if the points were wider apart.