Absolutely; and, just like stop signs and traffic signals it is important for drivers, pedestrians and cyclists to learn the rules for roundabouts.
No. Other than sharing a circular shape, a modern roundabout operates much differently than other traffic circles, including rotaries. A modern roundabout requires entering traffic to yield the right-of-way to traffic already in the roundabout. This keeps the traffic in the roundabout constantly moving and prevents much of the gridlock that plagues rotaries. Modern roundabouts are also much smaller than rotaries and thus operate at safer, slower speeds. The design of a modern roundabout allows capacities comparable to signals but with generally a higher degree of safety.