>>1. DO I NEED TO CHANGE or ADD any additional command for SBT_ backup.?
Yes, configuration should be something like
CONFIGURE CHANNEL DEVICE TYPE 'SBT_TAPE' PARMS 'ENV=<tape Env>'; ==> configure tape Environment
CONFIGURE DEFAULT DEVICE TYPE TO SBT; ==> Direct backup at tape
CONFIGURE DEVICE TYPE 'SBT_TAPE' PARALLELISM 4; ==> it will allocate Channels
>>2. controlfile autobackup is to +FRA01 do i need to change to SBT ?
Yes, if you want to take whole backup at tape control file backup should be with the backup set
also check the link :7 Making Backups with RMAN: Advanced Topics