Learner,
1. CTP also checks the components availability although main aim is creation of new order and scheduling. If CTP can also check the components availability then what is the need of activating MATP ?
You don't normally activate MATP and CTP at the same time. So, the answer to your question is "no need, when CTP is being used".
2. In BOP --I want to put a sorter based on customer priority. How can I technically take customer priority from ECC to APO ?
??? Priority (LIFPRIO) is already in the default field catalogue. You don't have to do anything special. Check out the 'as delivered' SAP Standard BOP Sort Profile "SAP_STANDARD" to see an example of LIFPRIO being used.
Best Regards,
DB49