Here is a good start. Cloudmaker did a good write up...
https://cloudmakertech.com/learn/temp-control/
And I thought this was interesting from a Ti wire maker...
http://www.sweetspotvapors.com/category_s/1854.htm
Basically... TC is going to limit power. The vapor production will be what it will be. It is carrying away. Basically cooling the coil. Heat input is driving the change of state between liquid and gas. So for a given set up, it will do what it will do, and then anymore power is going to heating the vapor. You want that limited to a certain temp, so the mod has to cut power.
From my understanding, more power in TC will drive speed, not necessarily vapor production. More power, or lower resistance will get the coil to temp faster, but then it is limited to what you want. It doesn't mean you can't make enough vapor. It depends on the tank. But it does mean you are limiting the output at some point.
The joules is power... watt-seconds. It's the same thing. So the power/joule setting you use will heat the coil faster. The temp limit is what you feel. So anywhere from 350F-550F is what I'm seeing people use. A wide range to a wide range of people and what they want. Set it for what you want and see.
The dry cotton burn test is another thing. Cotton burns at about 410F. You can set your box, and build a coil and see when cotton burns. not all these boxes are accurate in their range from one to the other. Keep upping temp till it burns, drop it 10F. But don't think that means anything higher will give a burnt hit. that's dry cotton... even if the atomizer is starved for juice, it still is wet. It is just a rough idea of what your temp is at. As long as your atomizer flows all the juice the coil can vaporize... you will not get a burnt hit at 600F.