1.5 gallons cover about 65 sq. ft.

You will need 4 gallons for your base coat. And 8 gallons for your metallic marble coat, or "money coat" as we like to call it.

Its clear. You will have to purchase the color separately. You can Search under Metallic stain. Sold by the same people. They have a lot of colors to choose from.

Figure 6 gallons of Neat Coat Epoxy covering approximately 250 sq ft (Prime Coat & Marble Coat Combined).
Your are getting around 125-135 sq ft a gal on Prime Coat & putting it down at 60-65 sq ft a gallon of Marble Coat.
Metallic Pigment needed:
Prime Coat = Gallons of Neat Coat Epoxy needed on Prime coat X .33 = Bottles of Metallic Pigment needed in Prime Coat.
Marble Coat = Gallons of Neat coat Epoxy needed on Marble Coat X .66 = Bottles of Metallic Pigment needed in Marble Coat.