stick a roman candle in it
stuff extra sharp cheddar cheese in it
force an elephant to stick it's tongue in it
No.
You will burn up your appliance!!!!!
Don't be stupid. No.
No, it is not safe to plug a 120v 20 amp welder into a 240v 40 amp outlet. The voltage difference is too high and could damage the welder. It is important to match the voltage and amperage of the welder with the corresponding outlet.
You'll need a power inverter. You can plug it into a 12v outlet and it has an AC plug outlet you can connect the fan to.
You can, but your circuit will be "protected" by a 30 amp breaker. So you'll have to consider the safety issues of having wiring and appliances that can draw up to 30 amps before tripping the breaker. Will the wiring and circuity support that much current without damage? If not, then switch to a 15 or 20 amp breaker.
no.
Don't!
yes. but DO NOT do it the other way.
Off hand no but your explanations are not clear as to who is doing what to whom,,
"As far as charging the Toyota Camry Hybrid, you can plug it into any one of the standard 120V plugs.So as long as it can surge a 120V plug, then it can be used."
NO, unless you get a converter that converts 220 to 110.