Duplicating a Database with RMAN

Question

I would like to duplicate to the same server Oracle Database with RMAN. I've configured flash recovery area for Oracle Database. My database is using SPFILE as shown below.

SQL> SELECT DECODE(value, NULL, 'PFILE', 'SPFILE') "Init File Type"
FROM sys.v_$parameter WHERE name = 'spfile

SPFILE

My questions are:

1. if my source database uses SPFILE then do I have create a PFILE from the SPFILE? If so, how can I do that?

2. What do they mean by this?

   You only need to create directories that are referenced in the PFILE or SPFILE.

   Which directories need to be created?

   Production Database : /u01/app/oracle/oradata/DB11G/. My SPFILE (spfileDB11g.ora):

   DB11G.__java_pool_size=4194304
   DB11G.__large_pool_size=4194304
   DB11G.__oracle_base='/u01/app/oracle'#ORACLE_BASE set from environment
   DB11G.__pga_aggregate_target=155189248
   DB11G.__sga_target=264241152
   DB11G.__shared_io_pool_size=0
   DB11G.__shared_pool_size=171966464
   DB11G.__streams_pool_size=4194304
   *.audit_file_dest='/u01/app/oracle/admin/DB11G/adump'
   *.audit_trail='db'
   *.compatible='11.2.0.0.0'
   *.control_files='/u01/app/oracle/oradata/DB11G/control01.ctl','/u01/app/oracle/oradata/DB11G/control02.ctl'#Restore Controlfile
   *.db_block_size=8192
   *.db_domain='localdomain'
   *.db_flashback_retention_target=720
   *.db_name='DB11G'
   *.db_recovery_file_dest='/u01/app/oracle/fra'
   *.db_recovery_file_dest_size=3221225472
   *.diagnostic_dest='/u01/app/oracle'
   *.dispatchers='(PROTOCOL=TCP) (SERVICE=DB11GXDB)'
   *.log_archive_dest_1='location=/u01/app/oracle/archive_logs'
   *.log_archive_format='db11g%r_%t_%s.arc'
   *.memory_target=417333248
   *.open_cursors=3^AC^@^@C"^@^@^D^@^@^@^@^@^@^@^@^@^A^DU^F^@^@00
   *.processes=150
   *.remote_login_passwordfile='EXCLUSIVE'
   *.undo_tablespace='UNDOTBS1'
   

3. if backup files (autobackup and backup set) are in a different path on the source host (not default FRA Path) then how can I use the duplicate command? BTW, only the flashback logs are in the default location (/u01/app/oracle/fra/flashback). Path: /u01/app/oracle/oradata/DB11G/autobackup and /u01/app/oracle/oradata/DB11G/backupset.