Despite what the climb was probably originally named for, I'm pretty sure the double crux is the mass amounts of shed snake skin in the ferns halfway up the climb, which I assume means a nest? And then the poison ivy vine growing in the crack at the top. Double Crux.
The obvious crack between Marlinspike and Ancient Way. Right side on top of the Northern Cave Slab. When the crack splits around a large block take the more protected (and easier once the holds become clear) route left.
Standard rack. Anchor options up top are limited. Get creative or use the solid tree set far back along with creativity for redundancy.