a) If you are not rushing to be a PhD, I think that the idea of having a MA in Math is great.
If you want to enter to a top program, you'll need a little more than 760 in GRE quant. Try to get at least to 770 since they use the GRE as a way to automatically reject people. It won't be use to compare you to another student but you'll be rejected if you have a score below the boundary fixed in that year.
c) The only people who can tell your chances to enter to a determined program are the faculty in your university (or the faculty in your target university if you know someone), specially, your recommenders, and other students from your school that have been in the process. They are the ones who know the history of placements of your institution and what relations have your people with the institutions you are targeting. If one of your referents know relatively well a professor in the other university, and your referent aproved that you are going there, you can be almost sure that you are in.
