The descending node uses the same symbol upside down, called the dragon's tail. Draco is nowhere near the ecliptic, the plane of earth's orbit in the sky. Hydra however is close to it at two points, its head and tail. Corvus is a crow. The shape of the constellation, at least how most connect the stars isn't very crow like, the odd box shape is quite distinctive and easy to spot.
Crater is a cup.
It is a Latin name. It is also used to describe those cup shaped depressions on the moon. There is a story that relates Hydra, Crater and Corvus which comes from Greek mythology. It seems the god Apollo had a pet crow. Crows are very intelligent birds, and back then, according to the story, they were white.