Okay. I'm working on her bio now, but it's not looking too much better than what I have posted. xD
I'm still trying to figure out how advanced her technology is, and how she will be able to watch the hereos' backs at all times. I'm kind of stuck on that part since I'm not sure how much access she can have to outside technology. At first I could explain that she has access to a satellite of some kind, which would be a good explanation on how she can observe the entire city with minimal equipment. But the question remains on how she has personal access to a satellite that is able to get highly detailed images of what's happening miles away without any delay. I would imagine that she could be using a NASA satellite or something, but how she could use it without NASA knowing is beyond me. I would imagine that NASA wouldn't appreciate unauthorized civilians using their technology to spy on criminals, no matter the cause.
Another option would be to simply hack already existing cameras around the city, like traffic light cameras and such. But again, I'm not sure how she could do this without getting into trouble. I would imagine the police force would have some sort of software that would prevent hacking into their computers, and would be able to trace the origin of the hack to my character.
Of course, you could simply say that she installed her own cameras all over the city. But this brings up some problems as well, like how she got the money for so many cameras and how did she install them. I wouldn't see why she would need to install so many cameras if her original plan was to be a solo hero.
I'm not entirely sure how to make this work without making her too unbelievable...