A fouled plug could cause a misfire, but it should be resolved by changing the plugs. If one particular plug regularly fouls there could be a problem with that cylinder. It could be a number of things causing it, but you’d need to inspect the cylinder to know for sure.

Prices for replacing key fobs vary. You can talk to your dealer about your options, but there are also a number of other places you can get your key fob replaced. You can read more about how to replace your car keys here.

It could be anything really, but I doubt it's the flywheel. If it's a clutch throw-out bearing it should get worse when you depress the clutch pedal.