Ancho Reyes is a brand of chile liqueur. There are other brands available, but Ancho Reyes is the easiest to find. It's made from ancho chiles. They also make Ancho Reyes Verde, which is made from poblano chiles.
The Fleur de Sel pieces are rather large, which is why it's helpful to crush them further in a mortar and pestle. They stick to the rim of the glass better when they are smaller.