Youll need to check drive and weapons independently.

During Tech Check it will be done without gas, but your valves will be tested via audio. You can however at the start plug a motor into each channel independently and test all channels using a single motor.

If the regulator fits directly onto the CO2 supply, then no. However youll need to double check with an EO depending on how your system works.

Yes, only advice ill give is to get the self reseting type.