Not that I want to discourage you, but it's not easy to get in. Top 30 is much more likely. If you want more answers, you should give more information first.
1. no use, math classes are more useful if you have that much time
2. Gmat >700, GRE >V600/Q800
try to go to the business college in your current school, find the best research finance professor there, tell him your goal, and be his Research Assistant so that 1) you have valuable reserach experience in finance, 2) you will get a good recommendation letter, and 3) you will know whether you like finance research and you will have better things to write on your statement of purpose
try to go to the business college in your current school, find the best research finance professor there, tell him your goal, and be his Research Assistant so that 1) you have valuable reserach experience in finance, 2) you will get a good recommendation letter, and 3) you will know whether you like finance research and you will have better things to write on your statement of purpos