Have mumps been eradicated?

No. The only infectious disease to have been completely eradicated is smallpox. Compared to smallpox, the measles virus is considerably more contagious, capable of causing large outbreaks even in population with high vaccine coverage.
No. Unfortumately due to people not being booster immunization may help. In addition to tender swelling of the parotid salivary glands, it has a number of possible complications including male sterility, arthritis, encephalitis, meningitis, pancreatitis, and heart failure. Immunization is still the best prevention.
No. Mumps outbreaks still occur, occurring primarily in those who have not had the full series of vaccinations against it. In addition to tender swelling of the parotid salivary glands, it has a number of serious possible complications including male sterility, arthritis, encephalitis, meningitis, pancreatitis, and heart failure. It is well worth being vaccinated against it.