I find the cables to be much easier than the rigid locks because you don't have to jiggle the whole lock around to find that magic angle that will allow it to pass through the things you are trying to lock. All in all the cable adds a few more degrees of usefulness to the traditional rigid lock style.
Yes, it will fit through the holes in a zipper. The hackle/shaft appears to be a small strand of airplane cable crimped to two metal pieces. It is the crimped pieces that hold the hackle to the lock body.
keep in mind that these locks work great but can be a challenge to get open at times... so you may want to give more consideration if this is being used to lock a gun case that you might need immediate access too
Looking at my ruler I see 10 mm in a cm, so the cable is 2 mm thick. When the two zipper pulls on my luggage come together, a circle from each overlaps one another. The cable fit through this circle easily. Hope this helps.