Configuration information is in sys.configurations.
Logins are in sys.server_principals (sys.syslogins is deprecated, should not be used)
Database users are in sys.database_principals (sys.sysusers is deprecated, should not be used)
Permissions are in sys.server_permissions and sys.database_permissions, depending which you're looking for.
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability