Black

Black, just like white, is not a color.

Colors have three dimensions:
Hue, value and chroma.
Black is undoubtedly a hue.
As far as value goes, it is the darkest of all values on the scale, but it cannot vary in value like colors can. As soon as it is a bit lighter, it is not black any more.
And chroma, or intensity is fixed too, there is no blacker than black.

In painting, black has to be treated with a lot of respect. First of all, black easily dirties other colors. Also, black objects show a variety of color and values where the light hits them and it is important to look carefully to determine the hue of those colors. The most illuminated spot on a black object can be lighter than the darkest shadow on a white object.
I hardly ever use black (I believe there is still some paint in the one and only tube of black I ever bought), but rather mix the colors to interprete black with the three darkest transparent colors on the palette: Alizarin Crimson, Ultramarine Blue and Viridian Green. Real Black is only needed in the deepest of all accents, where no direct, nor reflected light hits the object.

Abstraction vs. Realism

There is no right or wrong in art. Both representational and non representational art can be good or bad. Good art, at least for me, is one which creates a response in the viewer which is similar to the artists own initial impression or intent in relation to the subject matter.
Even though I paint representationally, I am always using a certain degree of abstraction. Nature is three dimensional and my canvas has only two dimensions, so, by definition, I need to abstract. How much I want to stick to what I see or how far I want to simplify is up to me and they way I feel that day. Sometimes I enjoy playing around with both abstraction and figure in a painting. It is just a matter of shapes and colors put together in a harmonious way.