+1.
Heat rises, and you want to blow out hot air. I'd make sure the intake and outake holes are also on different SIDES of the box, that way the cool air from the bottom has to cross the middle (ideally across the top of the bulbs) to help dissipate head. It won't do you much good if cool air is sucked in the bottom, goes up the side in pure laminar flow, and then out a fan without mixing with the hot air inside the box!
If you've got two, I think it probably makes more sense to run both blowing air out, rather than one in and one out. That way you'll nearly double the effective ventilation.
Light-trapping the air intake and outtakes is a good idea for max stealth.
As to which way the fan is blowing, that becomes instantly obvious once you turn it on!
