Is Masters in Public Policy really worth it?

[ssr1989]

So I graduated in Mathematics from University of Delhi, India and am a fellow at Young India Fellowship. I have worked with a couple of think tanks and would like to work in the social sector, which is why I was considering MPP. Problem is I have really low scores in my undergraduate program, though my grades in the fellowship program are way better. So I have the following questions:

1) Would my grades in the fellowship program be considered before my undergraduate scores? If not, how much could the work experience and my GRE scores compensate for them?

2) Is MPP the best program for me? Or Should I be looking at programs like Economics, Sociology or Political Science? In that case, how would my work experience and grades play out?

3) How important is a PhD in public policy? If I am not wrong, not many people go for it. And how would that compare with a PhD in other three subjects that I mentioned?

4) Finally, what could be the expected salary that I might take away after an MPP?