this torch is probably a Trafimet model:
Plasma cutting torches
Also fitted on the the (italian) Telwin plasma cutters.
Their site has some info on the startpulses.
Regarding your questions, as far as I know: yes, it is high frequency, yes it is high voltage, yes much noise (electrical interference) into your system.
I have had a Telwin Technology plasmacutter for a while. It is not intended for cnc use. It worked on my mach3 controlled table though (a little low on duty-cycle).