hi i'm billwelcome to just answerplease remember I am NOT there in front of you! my answers are based on your information
the oil pressure sender is located in the rear of the engine on the passenger side next to the distributor you will need a special socket to install it without damaging it, it is called a deep oil pressure sender socket, here is a picture looking from the REAR of the engine,the only problem you may have is releasing the red slide lock it can be easy or difficult i clean the connector first then slide the red lock over and release the connector.
well first the oil pump is a RARE failure and when it fails the engine fails with it since the engine relies on the oil pressure created for proper lubrication, NO lubrication the engine at minimum starts to knock once it starts to knock the engine has been damaged and will require a tear down to determine how much damage.
when the sender fails it can leak oil (severly in a worst case scenario) it also will sometimes show oil pressure and sometimes not sometimes go to full oil pressure then back to a normal reading.
the oil pump once fails there is little or no oil pressure ever and the engine makes noise.
sending units are very common oil pumps not so much, this is assuming the oil is changed regularly and teh engine was taken care of