I have an Antec PP412X as well, though that in itself doesn't make me an expert...
1. POT--short for potentiometer (I hope I spelled that correctly). It is a 3-terminal resistor with an adjustable center terminal used to adjust your voltage(s).
2. I haven't opened my PSU to know for sure what color they may be, but most that I have seen look like a small silver/chrome box with a hole in the top in which a [possibly colored] plastic 'screw' is located.
3. The 'screw' has a slot where you would insert your straight bladed screwdriver and turn one way or the other to adjust your voltage.
4. Possibly--but it would end up heating up the rest of your system because you would then be blowing warm air (heated by your PSU) INTO your case. Most cases are set up to suck in cool outside air from the bottom and as the air flows up the case, the air warms from the components inside and is blown out the top through your PSU. Airflow is facilitated by the tendency of warm air to rise. Since PSU's are usually don't fail due to overheating, they are located at the top of most (tower) cases because they generate so much heat that would otherwise be detrimental to the more heat sensitive components of your computer. If you believe you are having heat problems, add fans to blow air into your system from the bottom and fans blowing more warm air out from the top. Your airflow in should roughly match your airflow out (neither positive or negative pressure inside your case).
If your Antec is failing, I would suggest that there is some component failing rather than attributing it to a heat problem. Though, if you are already inside your PSU, make sure that you clean all the dust out--PSU's are veritible traps for all sorts of junk ranging from dust, to spiders (and webs and eggs), and cigarette smoke residue. Blowing and wiping out the insides may clear up any overheating problems and also solve any shorts/drains to ground caused by unwanted debris.
