30
If your extension cord is truly a 30 amp cord then it is composed of #10 wire. #10 wire is rated at 30 amps. All you have to do is remove the 30 amp plug and receptacle ends from the cord and install 15 amp cord ends.
yes
Yes. Assuming everything is wired correctly and your 30 amp AC cord is compatible with your 50 amp plug, you can do this. I think you will find, however, that your 50 amp plug has a different pin configuration than your 30 amp cord end. This is not easily resolved because there are serious dangers in going the other direction, plugging a 50 amp appliance into a 30 amp receptacle.
If it is a 30 amp breaker then it is a 240 volt outlet.
circuit breaker fuse
Two single-pole 30 amp breakers tied together make a two-pole 30 amp breaker. From this you can power a device that requires 220-240 volts, typically.
Replace the 30 Amp Breaker with a 15 Amp breaker.
Yes.
30
Yes, a 30 amp breaker is a 30 amp breaker. It must however be able to fit the box it is installed in.
If your extension cord is truly a 30 amp cord then it is composed of #10 wire. #10 wire is rated at 30 amps. All you have to do is remove the 30 amp plug and receptacle ends from the cord and install 15 amp cord ends.
5 amp,10 amp, 15 amp, 20 amp, 25 amp, and 30 amp.
yes
Yes. Assuming everything is wired correctly and your 30 amp AC cord is compatible with your 50 amp plug, you can do this. I think you will find, however, that your 50 amp plug has a different pin configuration than your 30 amp cord end. This is not easily resolved because there are serious dangers in going the other direction, plugging a 50 amp appliance into a 30 amp receptacle.
Not a good thing to do! If you are blowing 10 amp fuses, you have a problem with that circuit. Putting a 30 amp fuse in its place can do more damage.
No, you need a 30 amp breaker (whether that's from a generator or not it doesn't matter) with the proper voltage.