How should I organize a workspace to take my handedness into account?
Lamp on the left so that your work hand doesn't block your light, which is more probable to be the case than the other way around.

As far as the vice goes, I'd say it depends on how you orient it and if there is a wall on the left or right side.  If there is no wall on either side, I'd put it on the front-left so that it is near the lamp, and because if the lever arm is at the front of the desk, you could walk to the side and torque down on it with your right hand that way.

If there's a wall on the left, I'd put it on the right, but with the lever arm on the side rather than the front... again, so that you can stand to the side while torquing the lever arm.  Only problem with that is that your lamp will be at the opposite corner, but if it's easily moved, that wouldn't be a problem.