Double Kayak Storage Straps System Comes with 2 Carabiner Paddle Clips

How far does the lowest strap or kayak hang down from the ceiling?

What size holes would I need to predrill in order to get the hooks in easier into concret?

Has anyone used this for outside storage? Will the straps and clips hold up for the summer?

Can I screw the J hooks into a concrete wall pre-drilled with a masonry bit?