For the burning oil smell check for an oil leak. For the clicking sound, there could be a solenoid acting up. If this is a turbo engine, then I would suspect the turbo control valve which is near the air filter housing is the culprit. For your sun visor, well you need to replace it. And the last item that cover is usually called the belly pan. You will need to buy a new one with new bolts if you dont have the old bolts?