Check the Idle Air Control (IAC) and the EGR valve. Either one or both might need cleaning.
It can. But it could also be a number of other things. My car recently had this problem, but it turned out to be a firing problem and not the converter. so i'd say have all the cheeper stuff checked first.
Check all vacuum hoses. You should be able to hear the hiss.
No, very doubtful.
Check the catalytic converter for leaks.
Having no catalytic converter installed is illegal and can cause a myriad of problems. Probably not a backfire though.
Yes, internal coolant consumption can damage a catalytic converter.
No, the catalytic converter is downstream from the EGR valve so it has no effect on it.
Yes
No, the catalytic converter has nothing whatsoever to do with your defrost system.
A bad catalytic converter can cause hard starts if it has become clogged. This produces excessive back pressure in the engine.
A bad coil can damage a converter. If the engine is misfiring, it will cause raw fuel to get into the converter and that can cause failure.
No
Yes
yes it can