I have a few questions about the Passport Plus. I have owned mine for close to 2 years and recently started using it more an more, previously I just used it to tack stuff up then took them to the bench to TIG weld.

Whats the best gas to use with the Passport Plus in steel (CO2, C25 or other mix), stainless steel (Tri-mix or other) and aluminum (argon or other)? Can I use CO2 or C25 to make tacks on stainless steel?

Secondly comes the internal CO2 bottle, recently I have been taking this on the go and love having the portability. Can I purchase the adapters to fill the CO2 bottle myself, if so anyone have links for the connections? Secondly can they be filled with mixed gases or argon? If not are there any mini-bottles out there that can be filled with a mixed gas or argon?

I think thats it for now thanks!