If you are slow and sure the bend comes out perfect but one on this one didnt however you can panel beat the annealed channel and file/sand it flat if it does wrinkle slightly as shown in the pics below.
Before:
After:
For the height I used trial and error. I basically had someone hold the MDF in place and sat in the drivers seat and took the view that the top rail being in line with the upstairs windows of the houses opposite me, ~20m away, worked well which was 13" as it turned out. My fly screen is 4" and when sat in the drivers seat I can still see the nose of the car above it.