Now, in an situation where DB is in use 24 * 7 and size in few TB’s then how to plan for backup’s. I mean every weekend level 0 won’t be possibleYou can use rman feature to roll forward image copies. In this case you need to perform level 0 database backup only once.
Where there are good number of users or where there is business lose due to slow performance. What would be the RMAN backup Strategy
and apply archives generated till now for that particular tablespace ?As you are doing "complete" recovery to the current point in time .... yes you can use such tablespace backups.