I voted "above" but the cheekbone isn't the landmark I use.
The top strap fits just below the round part of the horse's cheek/jaw.
The lower part goes on the chin-side of the bit.
To me, the point of the figure-8 is to create a noseband that restricts a gaping mouth differently and more gently than does a crank, flash or dropped noseband. Ideally, the horse begins to open his mouth and feels constriction at the top first. Then you don't have to really crank either strap down hard in order to get what you want. Or with multiple points of pressure, the whole figure 8 can be looser and still get the job done.
Yes. Figure 8 with rings can sit on the cheekbone- even fairly high up under the eye- and still buckle properly below the jaw bone. A figure 8 without rings will sit just below the cheekbone (but not 2 fingers below like a regular caveson). You have more flexibility with rings.
I fit my figure 8 with rings like that. Here is a picture. Without rings fits like the picture Peggy posted. I prefer w/ rings because the top band fits better with rings, IMO. There is no gapping like without rings.
"I am witty. Ask around." --Pat, COTH
I fit the ones without rings just below the cheekbone, and the ones with rings about 2 fingers above. I try to adjust it so the disc is exactly in the middle, not too high or too low. Here is a picture, although this isn't the best example because the noseband on this bridle is ridiculously large and I couldn't adjust it any higher on his face. The one in the picture is a Collegiate, but I upgraded over the summer to Five Star Tack's Chelsea model and it's a lovely bridle.
My boss, who's British, calls all figure 8s grackles (rings or no rings).