There are no function-specific heatshink. A heatsink is a heatsink is a heatsink. "Hanging" doesn't hurt anything as long as it's not in the way or shorting anything. And more for your party conversation

The most efficient heatsinks are the one with the most surface area. The same size heatsink, one with 16 fins is more efficient than one with only 8.
Since you mention VRM, if mounting this in a tower case, so the heasink will be ending up sideways? I dunno if the double-side tape that some of these include will be sufficient to keep it in place for the long term. If no screw mount available, I would trust more plain heatsink (no double side tapes) with heatsink adhesives.
Also, if they are going to be sideway, and you have one...