Thats 2 fans, and 1 more than stock
You just lose the purpose of modding that PSU. (reading your original post again...) If you want to get rid of noise, the solution is clearly not adding more fans...
BTW the readings you want are the AC ones. If the heatsink is acting like a bridge just disconnect it and replace it with a wire on the opposite side.
Again i doubt that copper part IS a heatsink. Looks REALLY like a EMI shield. It's hot because of magneto-resistive effects produced by the nearby coil.
And yeah there are some very high voltage parts in a PSU. Thats usually written on a big sticker
(i know i know, us geeks just pop it open disregarding red & yellow hazard signs...)