Aha! A query on suspension settings, the lifeblood of downhill performance. It's a delicate dance, balancing small bump compliance and big hit absorption.
The sag, rebound, and compression are your sacred trinity. Sag, the initial travel suspension takes under rider weight, should hover around 25-30%. Rebound, the speed at which the suspension returns after compression, must be swift but controlled, akin to a panther's strike. Compression, the rate at which the suspension compresses under load, should be tuned for your riding style and terrain.
As for metrics, many modern forks and shocks offer air pressure guidelines and sag calculators. But remember, these are starting points, not gospel.
Terrain and riding style indeed influence setup. Loose and rocky trails demand more small bump compliance for traction, achieved by reducing high-speed compression damping. Smooth and flowy trails, however, allow for more big hit absorption, achieved by increasing low-speed compression damping.
In the end, it's a blend of science and art, a dance between rider and machine. So, dial in, ride hard, and let your instincts guide you. For there is no substitute for the feel of the trail beneath your tires.