If you paint the walls the way your talking about. it's sure going to be dark in there. The lighter the color the brighter the light will be. As for the layout, lay it put on paper for the best layout that will work for you. where you going to have your saws, welding stuff, air comp, heat, disign it for a lift,(incase you buy one later)
which spot is going to be your work area, which spot is going to be your park area.