Failed Oil Pump or worse?

My 97 Buick LeSabre cut off on me after driving it for less than a mile. I noticed that the car was leaking oil in the driveway, so I was on my way to a mechanic when the oil pressure guage started fluctuating and slowly dropping. I put oil in the engine and when I checked the dipstick I found that the engine was full of oil, past the max point. So I proceeded to drive it, but not even 2 minutes afterwards the oil pressure guage continued to drop and I began to hear a knocking in the engine. I tried to make it back home, but the car cut off on me about a mile from my house.

At first the engine would turn over and then cut right back off, now it won't turn over at all. I recently replaced the camshaft position sensor and got a new battery. The oil pressure guage currently sits in the red. I don't have the money to take it to the shop, so I need detailed advice so I can fix it myself. Scraping the car is not an option. I have access to a DIY garage equipped with every tool I could possibly need. I have been told that the problem could be the oil pump. I want to make sure this is correct so I don't have to continue to spend time fixing the vehicle, I need it up and running by Wednesday. It's got 167K miles on it. Once I replace the oil pump, will the car be fully functional? Are there any other things possibly malfunctioning? If so, what else could be causing these problems and how do I go about repairing the car? Thanks for your reply.