YES IT WILL
Having no catalytic converter installed is illegal and can cause a myriad of problems. Probably not a backfire though.
Engine mounts
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.
A bad catalytic converter will cause a severely restricted exhaust system. You would notice a lack of power and performance from you vehicle and in cases of a completely blocked converter, the engine may not run.
A defective catalytic converter can do that.
If the converter is partially clogged it can cause the engine to overheat which can cause serious problems. Other than that if will not harm the engine.
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.
The converter is plugged and needs to be replaced
the answer is no . the converter would not affect just one cylinder .