LFT
I currently work in India for Kingfisher on their Airbus fleet. I too am an OCI holder, but from the UK.
To answer your points:
1) Yes - if you are Type rated at mimimum, then you can work as an expat F/O
2) If you acquire an OCI you will be employed as an Indian on local terms, which frankly are not that different to expat F/O terms. However, you will receive more benefits
3) You need to have passed maths & physics at an eqivalent level in accordance to where you were educated. e.g A-levels in the UK
4) No
Good luck
HPC