Postage stamp sized pics

Link to case's home page, please

I did take a quick look at Silverstone and Lian Li and didn't see a similare case. It is aluminum?
The stock CPU cooler will not starve for air with a 120 PSU fan facing it. Small fans will pull more mm of h2o because of thier higher fan rpm...Generally.
If you used a HS like a SI-120, you would want atleast 2" between the PSU and HS's fan.
Those side fans are vented through the side cover, are they not? So you'll have plenty of intake air.
If you decide to get a PSU with an 80mm fan there are two things which will quiet them down.
1-On the wall behind the case tac up some thick carpet or soft cardboard eggcrate, like 18 eggs are packaged in...Works.
2-On the intake grill, next to where the harness exits, bond a 80mm fan that puts out 30cfm. This will cool down the secondary HS where the units thermal control generally is.
I used a Zalman 80x15 on my Zippy and feed it 5V but if I were to do it again, I'd get a Arctic Cooling 80x38 from Provantage.com. It's damn near silent at 28cfm. Don't use a straight bladed fan, use one with cupped blades because they will drive air through fins/grill work better.