There’s no magic, just use finer and finer sand paper, I’d start with 1000 grit and go up to 7000, end with plain copier paper for the mirror finish. Try not to touch the reflector cups while sanding, if they got scratched/fingerprinted you will loose light.
No.
I think for good polishing you need to take out the optic. Then put the sand paper on a very flat surface and sand the optic on the sand paper. Once taken out you are in danger of touching the back side which should stay extremely clean and preferably never touched at all.
Is it only coming with the frosted optics? I remember seeing a few posts about Carclo options for this so I may just order a different for it at some point.
I believe so. If I remember correctly, the normal un-polished version produces an ugly beam but is throwier. A frosted one looks nicer and can be polished to give a bit more throw while still maintaining a pretty beam.
The D4S is much larger in the photo, but the shadows on the sides of the FW3A give a false illusion of being even slimmer.
Copy the photo, reduce the contrast, increase the exposure illumination and see the difference.