I issue
Select schemaname, username from V$Session;

Why do I always get at 8 users (without name) logged on to the SYS Schema? Are these some Oracle Background processes?

My second query is more basic. How can one have more than one user in the same schema? I mean when we create an Oracle user, his schema is automatically created with the same name. So why have two different columns (Scemaname and Username) in the V$Session view?