MANY people use HPS to veg & flower plants and get good results. As far as distance from the plant, use the hand above the plant method to gauge, meaning you place your hand above the plant and feel for heat, if your hand gets hot then its too close, move it up a little and try again.
As far as lighting you can throw a 6500k cfl or a couple side lighting of floros to give more light spectrum, but all in all you will be good!