Yes if it is totally clogged.
YesYes
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. A catalytic converter wont. If its a rear wheel drive, check your drive shaft. Front Wheel drive, CV Joints. Other than that worn steering. Exhaust wont cause this issue.
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.
Clogged converter, running too rich or a misfiring plug.
Yes
No