Yes, it can damage the engine.
The heat generated by the converter can back up into the engine and damage it. Cause it to overheat, blow a head gasket or damage the heads.
Yes, if it is plugged the exhaust can't get out of the engine.
The life of your catalytic converter depends on the condition of the engine and the fuel you're using. If the fuel has the wrong additives, the catalytic converter can become plugged up. If the engine burns oil the oil vapor will build up on the catalytic converter and it can become plugged. Otherwise, if the catalytic converter isn't plugged, don't replace it.
Check that catalytic converter is not plugged
Yes it can
Plugged air/fuel filter? Plugged catalytic converter?
Plugged catalytic converter?
Plugged fuel or air filter? Plugged catalytic converter?
A plugged fuel filter, A plugged catalytic converter,
Possibly a plugged catalytic converter.
Could be a plugged fuel filter or a plugged catalytic converter.
if cat is plugged an exhaust dont pass through it will stall the engine