If you have a leak this large, it should be fairly obvious as to where it's coming from. If there is too much oil and dirt around the area of the leak, then you can add fluorescent dye to the oil, let it run, then use a black light to find the leak.
Sounds like the oil is leaking into the engine cylinders. This is due to bad valve stem seals, piston rings or a plugged PCV System. You'll need to get this checked out by a shop to see what is wrong. There's a good chance the engine is worn out and will need to have major repairs performed, but only a proper diagnosis will reveal what is needed. Good Luck sorry for the bad news.
Check your belts. This car has two belts one for the alternator / water pump.The other drives the A/C and power steering.There is no backup belt for the water pump so when the one belt breaks and the car is not stopped your engine will overheat quickly since the head is made of alumium. Anytime you hear a loud squeak when you start it up or turn on the air con have the belts checked ASAP. It might just be a matter of tightening them to the correct tension.