Oil pressure light

The oil warning light should be on bright and steady when the engine is not running. If it's flickering there is a bad connection related to the sending unit circuit. Most often it is due to a bad contact inside the sending unit itself but there could be a poor contact in the electrical connector too. Disconnect the wire from the sending unit, then use a small jumper wire to ground the terminal. If the light is on bright and steady, replace the sending unit. If the light is still flickering there's a problem in the wiring.

That's a serious problem. That light means STOP THE ENGINE IMMEDIATELY. You need to first have the oil pressure checked manually to determine if the gauge is accurate.