1. If you're seriously considering Harvard, you need some decent work/internship experiences. Your current location in DC is great for getting these kinds of internships. I'd target the State Department's program if you're interested in that foreign policy type experience. Take Microeconomics; must policy programs require at least some coursework in that before applying to their programs. Statistics will be very helpful, as I know through a friend attending Kennedy that your first year is very stats heavy. Also start saving your course syllabi - Harvard requires a quant resume separate from your normal resume listing out all quantitative courses you've taken or quantitate skills you've used in internships/work experience/other coursework that could lean towards quant.
2. I say MPP as its a generalist degree or MSFS from SFS...but not sure if you want to be a double Hoya or if you want to leave the Hilltop. You're at Georgetown already, so take a look at the McCourt School's MPP. Their admin is in Old North but I think some of the support staff moved to CarBarn.