Thanks for the input, guys!
The opening in the front will be sealed. Two layers of either glass or plexi-glass to form a window.
I can expand the projector's chamber so it's a bit larger. Can't go too much larger though because the box is already pretty big.
The projector is a BarcoGraphics 4000 and is hella noisy. I doubt quieter fans could be installed in it. It seriously has 5 fans. This projector was given to me for free so I might as well make use of it.
The damping material I was planning to use is about 1/4" to 1/2" thick (automotive carpet padding). Not as effective as the 1" material by any means, but that's why I opted for the bends and turns in the channels. The bends by themselves should offer some harmonic damping. Kind of like how a horn or transmission line subwoofer's folds cancel out 3rd order harmonics. Unless I'm wrong, of course.
The whole box will be sealed air tight except for where I want the air to flow, so, in my mind, it doesn't really matter where the fans are. With the fans "pushing" the hot air out, the air will only have one place to go anyway due to positive pressure created by the sealed box. I can easily move the fans to the exhaust side though in the design if I'm wrong here too.
Far as the different models of projectors going in this box, I'm not too worried. The projector is large, which means any model of projector I buy after this one goes will be smaller (most likely significantly smaller) and will also generate less heat (this one has 5 fans for a reason). I figure that the air flow in this box should be enough to move the heat out no matter where the exhaust is located on the replacement projector...again...unless I'm wrong.
Thanks again for taking the time, gentlemen.