the baby hold a Indian Citizenship by default?
Ask at the Indian consulate in Warsaw. But I'm pretty sure that a child which has one Indian parent is Indian at birth. The kid most certainly will not qualify for a Polish passport (not unless either you or your wife have naturalised as Polish citizens, which I'm pretty sure would involve needing to give up Indian citizenship).
the baby gets any kind of benefit in his/her education being born in Poland?
As compared to being born in India and then coming to Poland before he/she can speak, no.