from a thermodynamic perspective,
to answer one question, radiation/absorbsion of heat is a two way reaction. That's how the silver "radiant" insulation works...how much light is emitted under the hood of a car, for example? None on the visible spectrum, but you will still see the silver wrap used around exhaust or air conditioner units.
If I remember right, the formula for the emission of radiant energy has a big exponent on the absolute temperature, so in other words, it doesn't make that big of a difference one way or the other at say, 170 degrees F.
Conversely, a 3200 degree F batch of steel in the foundry will throw off an amazing amount of radiant energy, which is why long pants and long sleeve shirts are the norm in this super hot environment. Anyway...
Remember, the heat radiated will be offset by the insulating property of the paint (it is basically plastic, which is a decent insulator) and its absorbtion of radiant energy from the sun and/or other objects around it.