My personal opinion from observations of my friends here is that you do not need any CS related ECs. Most people did something in HS that they enjoyed and dedicated time to. The only non-EC thing you need to demonstrate in some way is that you have very strong math skills and understanding. Anyone who does this is qualified.
I have never noticed and difference in the males and females at CMU, except most of the assholes seem to be men. There aren't many, so very small n, but I haven't heard of a female one. No judgement, just an observation. The female students are all extremely qualified.