Data Guard :: Parameters With Active Duplicate For Physical Standby

We are planning to create physical standby database for 4-node RAC primary to a 4-node RAC standby using Active database duplicate with ASM and OMF

1. while using active database duplicate, do we need to set cluster_database=FALSE in spfile clause and create standby,next change it back to TRUE at standby. Or we don't need to touch it. And also do we need to include instance_number parameter
2. We are using OMF, can we use log_file_name_convert parameter in spfile clause of duplicate. Documentation says log_file_name_convert cannot be used if standby is going to have OMF. Because we have 5 groups for each thread, which are on 5 different disk groups. When standby is created all the logs are created in only one disk group pointed by db_create_online_file_dest_1.
3. To enable force logging at primary do we need to shutdown the database?