Understanding Compression Ratio

I agree with the other post that you would expect more wear (high compression gasoline engine for example)than with lower compressions. The counter balancing effect in diesels is they are designed to run hotter. This means that the individual components must be LOOSER to allow them to tighten up with heat expansion. To seal the engine and maintain compression for fuel ignition more sophisticated oils must be used as the oil provides the only seal between the piston ring and cylinder wall in any engine. These same oils must provide adequate lubrication at the hotter temps and tighter clearence when the engine is at operating temperature. The looser engine and higher compression plus loss of heat to a cold block results in diesles being harder to start in cold weather. Listen to a diesel knock on a cold morning. To maintain the higher compression, more rings, of better material are typically (but not always) used. Especially if a turbocharger is used to increase manifold air pressure.

I don't know much about the other questions but here is my 2 cents worth. An engine with higher comp. ratio (diesel engine) is subjected to more wear, but such engines are made of better materials to compensate this. So they will last at least as long as lower comp. engines (for example gas engines). I would also think it is obvious that the high compression engine needs more and better piston rings than lower comp. engines.