Halides will give you intense light that should make some ripples from the top of the water shine to the bottom, which creates a fantastic ambiance. But, four 4 foot t5 fixtures will give sufficient light I would think. Consider the heat from three 250 watt lights. You'll need to shield the diners eyes from the light, the heat, and also protect the acrylic which will melt.
As long as all the Styrofoam is level, you can use multiple pieces. For a tank this size use the high density stuff, not the white foam.
As for a stand, I'd suggest having a custom steel square tube stand built for you. It will likely need to support near 13,000 pounds. A steel stand, even with many support bars on it, will allow you to put all the equipment below it. A wood design will need more support peices making the openings to the inside of the stand, smaller and more difficult to access.