hey! was your place of graduation Delhi University?
1. In GRE, quant matters more for MPA. Yours is above 160 so should be safe.
3. Most top programs such as HKS, WWS, NYU, SIPA are internationally-oriented. Also depends on what you'd bring to the table.
4. Public sector work in private firms and/or corporate social responsibility engagement isn't looked down on in anyway. However, the focus of the firm and the personal motives behind working on that English learning product will matter. It could come under social entrepreneurship. Which firm was it? Also, your involvement with the organisation during college (was it Enactus?) will matter equally if not more for the applications. Make sure to explore those in the essays.
You seem like a good candidate, and J-PAL definitely is an advantage. This was my two cents, good luck for your application!