Dear Mr. Ram Samudre,
Art. 15 provides for prohibitionof discrimination on grounds of religion, race, caste, s*x or place of birth.
Art. 17 provids for abolition of untouchability.
But, conclusion can not be drawn on basis of a single or isolated provision. Many provisions are to be construed harmoniously and in consonance with each other keeping in view part IV, the directive principles of state policy. In this regard, You may recollect a line from Samvidhaan Chaalisa - "Mantra mahamani lakshya gyaan ke, sab samvidhi sanshay nidaan ke." This line is devoted to part IV of the constitution.
Second part of your query is not relevant for this thread and any comment on it will change the track of the discussion. Hence, I am sorry , I prefer to abstain from replying on it. However,You may post an independent query / thread for it , I will try to participate with a proposition that discrimination can not be the basis or rule of any Dharma ( religion is not exact translation of Dharma) and there also, a single sentence from any epic should not be undestood in isolation.