The left leg is a loop, so he could have used a knot instead of adding two points of failure. Is the loop safer? No, if one strand fails, the anchor fails.
Yes, that's a caving rope, used for climbing, running it over a bunch of edges. Now, he had all this rope as an anchor, and left his climbing rope coiled, sitting next to this rig.
At a recent meeting organized by the Excess Fund, there were complaints of hammocks showing up at crags across the country. This one crosses the main trail.