The light is 471/3"Lx191/2" Wx21/2" D. As for heat it gives off little heat compared to Metal Halides . I never used a chiller on the tank. The tank is at work though and the office is cold in winter and A/C is run in summer. The light does not come with the acryllic lens or the mounting legs.
This is the light as for sale at J&L. The picture is of the 4 bulb fixture.
http://www.jlaquatics.com/product/sl...C+8+x+54W.html
Hope that answers your Questions
Chris