Probably some of the cheapest components that can be found in Asia, I'm guessing.
Yes, it's possible that adding resistance in the regulation circuit with the pot raises voltage. It's about how the circuit is configured and the pots resistance with relation to ground.
What you are seeing with the attached component to the aluminum plate is a transistor with TIM (Thermal Interface Material) attached to a heatsink. It should have no air gap between the transistor, the TIM, and the heatsink.
The white stuff around the capacitors is probably an adhesive to keep things in place or it may be a gob of anything dropped by the assembler. I wouldn't assume that is thermal grease.
Interesting to note that the traces on the board only reference ground to the case at one screw mounting location. It wouldn't have been that much more expense to allow for that connection at another screw through-hole. I guess when your plans are to make a few million of these....
All in all, pretty typical board for mass production.
