no but it may cause it to stall if exhaust is blocked
Exhaust of an engine is a gas.
It depends on the damage but most likley not
Depending on the vehicle, it could damage the catalytic converter over time.
Yes, it could restrict the exhaust and cause problems
exhaust?
This can be caused by the exhaust valve being either bent, worn or not seating properly. If this is the case then get this checked out A.S.A.P as this could cause severe damage.
For intake or exhaust valves; Lack of oil, defective valve, bent push rod, foreign object damage, etc.
An exhaust valve(s) staying open upon compression.
No but an engine running like that can damage the valves.
It would be unburnt fuel
Exhaust leaks close to the engine.