If your not concerned too much with appearance it would be worth looking at the shelving units at Lowes/HD. I have seen nice 4' wide by 2' deep units that fit the 4' shoplights very nicely. You could get some 6mil poly film and cover it. You will primarily be restricted to lowland plants as the shoplights do put off a bit of heat. I am not sure if it would be cheaper but might give you more space than the unit you were looking at with the vinyl cover.
Cool white tubes work fine with the occasional warm white for a little better balance. Yes you can use the growlux or the more balanced chroma/ultralum 50 bulbs but they are more expensive and not absolutely necessary.