The doc has been and will continue to be the pp code itself, I did my best to add copious self documenting comments variable names to the code, much to the chagrin of many that read it as I can be very wordy at times 
re. “first pierce +/- delay” is a time value in seconds that is added to the tool pierce delay. It’s usually a - value. It is intended to account for the fact that on the first pierce, the cool-down air is not flowing through the torch, thus the solenoid does not have to close in order to reset the blow-back nozzle electrode. This lessens the pierce time, which is going to vary depending on the brand and model of the plasma source. For PrimeWeld latest generation Cut60, this time is -0.07 seconds than normal pierce time. At some point since v5-13 I renamed it “First pierce delay delta +/- secs”.
re. “Torch Probe Proximity Distance, 0=off”, this is a distance value (mm or inch) from the last torch touch-off probe XY position, within which all subsequent start of cut positions will skip a torch touch-off probe cycle until the distance is exceeded, an event which makes the current probed start point the new reference point. Think of it as a radius to a circle in which immediate subsequent start points will not conduct a torch touch-off. It makes for quicker jobs.
See the pp posted here, its a simpler version without rotary function - Post Processor Example w Custom Options popup window - #14 by sheetcamCS2