It seems like they may going in that direction. With her and Kara being on the outs and Kara never telling Lena that she is Supergirl she maybe to dark.
It should be more of a question of when at this point. I don't want them to rush it but she definitely needs to go evil at some point.
I hope not... otherwise, her background so far would have 0 sense. Lena is not Lex and I certainly hope they do not lack originality.
Hard to say. It could go either way. I think it's a storyline that's on the creators' radar at the very least. It would parallel Lex and Superman a little too closely that they might avoid it completely.
I think it would make total sense. She's already headed down that path. She's not exactly the biggest fan of Supergirl right now and is already working on sketchy projects. We know she has a darkside. I think it's safe to say where things are going.