Charset

SELECT value$

FROM sys.props$ 

WHERE name = 'NLS_CHARACTERSET'

Other way:

Ordinary Character set

select value from nls_database_parameters where parameter = 'NLS_CHARACTERSET';

National Character set

select value from nls_database_parameters where parameter = 'NLS_NCHAR_CHARACTERSET';

Get Tablespaces

select tablespace_name,extent_management from dba_tablespaces;