A. Well though the Christian population in India is just 2.3%, you have almost all traditions of Christianity in India. Catholicism, Eastern Orthodox, Syrian christians, and all the protestant traditions. There wasn’t one particular era in Indian history when christianity spread, but it came in different waves. First when st. Thomas came, then the fourth century, then catholic missionaries, then colonisations by the French, Portuguese and the British and so on. So India does have a very unique christian history.
B. Yes you are right. There is a lot of social and charitable works done by both the catholics and the protestants. It is a way of impacting the culture. In many parts of India Christianity is almost synonymous with high quality schools (with very nominal fees for the underprivileged), Hospitals, Orphanages, Old age homes etc.
C. The best way to develop strong roots in India is definitely through Apologetics. It is time for Christians to engage confidently with the deeper philosophies of the different religions. This needs to be done at the highest levels. First in the major cities in India and I am sure it will trickle down from there. In a way that is what we do as the RZIM India family.
Another way is undoubtedly by showing Christian love. To continue to show the nation that christians are committed to the cause of the weak and the downtrodden. And finally it is also important especially in India to show the healing power of the Gospel. I do mean this in a wholistic sense. The Gospel brings us ultimate healing from the condition we are in, but it also meets our physical needs. As of now many charismatic churches are in the forefront of this movement. They are gaining a lot of traction and have millions of people joining the church (many of them from different backgrounds) but it is also at the cost of very thin theological thinking. These Churches need to be helped and backed with good apologetics and strong Christian theology.