Why there was a need of CAA before NRC?

Why there was a need of CAA before NRC?

We have seen in Assam that NRC has excluded more non-Muslims from the citizenship list than Muslims. There was a need to appease and protect Bangladeshi illegal immigrants who are mainly BJP voters. The CAA was also promised in the BJP election manifesto.
Moreover, CAA+NRC will be an additional tool to appease more Bengali immigrants in West Bengal state which is election bound next year. Winning West Bengal by the ruling BJP will be a big milestone for the Party.

What is the link between NRC and CAA?
These two are very  strongly interlinked. Without each other they both will be handicapped. See for example the claus 6 of the Citizenship Amendment Act to assertion how these two are clubbed with each other.
In Assam-NRC some 19 lakhs people are presently left out, around 5 lakhs are Hindu Bengali immigrants from Bangladesh. All of theme can be enrolled merely if they prove they are refugees and arrived in India before December 2014. However, remaining around 14 lakh, majority of whom are sons and daughters of the soil- indigenous  tribal people, from all religions including Hindus and Muslims, will remain non-citizens of India if they fail to prove again during the claim and objection procedure. It means CAA will give citizenship to those who came from three foreign countries and take away citizenship from those citizens who are indigenous Indians but do not have pieces of papers to prove it due their lack of education or being poor.

NRC without CAA is nothing, just a waste of national recourses and CAA without NRC doesn't make sense for BJP. However, the CAA already taken away the being "secular" status from India.

Is CAA against India's Constitution?
Yes, by all means it is. It is against the preamble of the Indian Constitution which stands on secularism as one of its major pillars. It is against Articles 13, 14, 15 and 21 of Indian Constitution. Read article 13 which prohibits enacting any law which may go against the basic principles of the Constitution and fundament rights, article 14 which speaks about equality of a "person" before the law and article 15 prohibits discrimination on the basis of sex, caste, religion, language or place of birth and the article 21 is about personal liberty of all citizens of India.
Until one is proven guilty Govt. cannot seize liberty of a citizen but in the cases of detention in Assam in the name of foreigners the same has not been followed, because if a person could not prove his Indian citizenship due to lack of documents with him, it directly does not mean that he or she is a foreigner unless the Govt. proves from which country and place he or she came from. Unless you do not prove he or she is a foreigner with evidence in your hand, you cannot punish a citizen of India. But you are punishing hundreds of people in Assam just because they couldn't prove that they are Indians  but you too couldn't prove they are foreigners. This same practice will not be done in reset of India is not assured.

When the NRC plan or details are not yet ready as the TIO reports reads (20 Dec. Online edition), then how the Govt knows what and how will it be and how not?

I don't know it. TIO might have the answer or it could be one more Jumla and propaganda from the HM.

If the NRC is like a simple documentation process as mentioned in TIO report then why the Govt. is going to do one more process after Aadhar which will be very costly and deadly tired some?
To divide Indians and rule. Just to keep Indians in line like they were standing during demonization so that they cannot think of or ask about development, economy, price-hike and jobs etc.

Thanks
MB Qasmi