I bought a used XMT 350 CC/CV ON EBay it came with a Q300 mig gun S64 feeder and a Weldcraft 17 series valved TIG torch. The power supply doesn't have the optional gas valve. But it came with a brass gas / power block.

For TIG I believe I understand that I can clamp a lead from the - terminal to the block and ground the work with the + terminal then use the torch valve and add a 14 pin control with either a foot or torch handle control if I wish to adjust the torch while welding.

1. Can I also bolt the power block to the same pole on my s-64 as the power lead from my power unit then plug the power plug to the - output and the ground plug to the + for TIG apps and reverse the plugs for MIG applications? Or does this potentially risk damaging something in the feeder unit?

2. How much money does it cost to convert the unit to one with the optional gas valve.

3. I also have a switch position for pulsed MIG but the inside cover indicates this is optional. how would I know if the unit has the pulsing option installed? If it is not, how much would this upgrade cost me? I have a long way to go to be able to use this equipment's capabilities but I want to start exploring.

I don't have a problem taking of the cover and installing options, I think I could leave the machine unplugged for 24 hrs to let any capacitors to bleed down then do the job. Is this thinking reasonable or crazy?
Thank you in advance