Skywalker Skywalker Signature Series Y Type Chimney Mount with 18ft Steel Straps

Are the small ends where the U bolts go set at 90 degrees to the part extending from the Y bracket to create a flat surface to attach a flat board to?

With this product, is it required to bolt or attach in to chimney? Also, is the 18 ft reported per roll, or total?

I just received this, I don't have instructions. Can someone please help.

Tightening the bolts, the clips slip so I crushed them down, now I need to relocate the antenna and need 4 more clips, can I get them from you?