A: 16.5mm from the top of the high leg to the inside surface of the base, 14mm from the top of the lower leg to the inside surface of the base
A: Per the photos in the installation guide, the U Channel should be installed with the shorter edge facing upward. We have never heard of drilling "weep" holes in the profile
A: If the masking is no longer on the panel, you can tell which side should face up by looking on the outer edges. On one edge will be an inkjet stamp. This side should face the sun.
A: Your local store can special order them if they do not have enough in stock or they can order more on a store stock order