Yes, in some form. In the United States, several religious organizations including the House of Netjer (www.kemet.org) and Neos Alexandria (www.neosalexandria.org) practice religion derived from ancient Egypt.
Yes, technically. It does still exist, but is not lived in.
its legacy does The city of Rome still stands - very different today to what it was then. The political body of Ancient Rome does not exist.
It is not used today no, and that is due to its complexity
The Hupa were a Native American tribe located in Northern California. Their religion is a traditional tribal religion, meaning that they still follow the religion of their ancient tribesmen.
Classical Egyptian