I agree with 'race' choice within the human race. Picking the tone of your skin seems likely (if we even get to see our faces), which it seems we will, but then again there are times I doubt this.
Race among the awoken or exo however, I don't see. Awoken are bright glowing people. Exo are robots. Why complicate it with race within race? Maybe you'll be able to change the hue of the awoken, or shade of the exo's metal. We'll see.
And gender choices are a given, literally, Bungie has said that the ability to pick gender is there, you can be a female robot wizard. And robot is the only one where it wouldn't make sense to have gender, and there is gender. So the other 2 races will surely have the choice to pick your gender.