Second question while we're at it, what is better for the tip to be dragged or held slightly off the metal? As much exp metal cutting, I do equal or more 4x8 16ga sheet metal cutting and until I build a CNC I do it all by hand with the plasma or circular saw. I want to build cutting jigs from either 3/16" or 3/8" flat bar that are the same shape as the parts I'm cutting. This way I can just set it on the metal and trace it with the torch to make a perfect part cutout instead of all the layout time it takes with a template, marker and straight edge.

3/16" flat bar puts the tip right on the metal.
3/8" flat bar allows the tip to be suspended nicely in the air, leaving about 1/16" gap between the tip and the metal being cut