Okay, a few things.
- Omae does have a kind of edge to it, and it is informal. Boku and kimi are also informal, without as much of an edge. Watashi is technically the "normal" word for "I," since it is formal, but regular "formal" in Japanese is the equivalent of most other people's "normal." The really formal would be watakushi.
- In this day and age in Japan, the "male" and "female" terms have kind of gone out the window. Like, for example, a lot of lessons will teach you that "chan" is a suffix used only in familiar situations for females. But that's certainly not the case. Many younger males use that, too. However, there are exceptions. Such as, I've never heard a female use the male suffix kun. And males tend to try not to use female vocabulary, such as atashi. Females, on the other hand, have recently begun to use male words whenever they want, like how Ayumi uses boku. So it's kinda confusing, but what I mean is...Don't take it too much to heart about gender specific words.
- When you're singing, you shouldn't worry at all about whether or not the song is directed towards a male or female, unless they are straight up singing about wanting to....make love. In that case, it'll be pretty awkward. But otherwise, like you said, it's pretty much just poetry. And poetry is not all about your emotions when you perform it. It's about creating a general atmosphere for the audience. So saying "he" or "she" when it should be the other isn't a huge deal.
- And I also thought this was a genderless song, hah.