There's several places the coolant fluid could be coming from:
1) the two block drain plugs (one one each side of the engine, close to the front of the engine and adjacent to the oil pan mounting bolts). One or both could be seeping and need to be tightened;
2) Any of the radiator or heater hoses could be leaking/dripping
3) The thermostat housing could be dripping/leaking as could the water pump itself
4) The top coolant by-pass pipe under the intake manifold could be leaking
5) The head gasket(s) could be leaking
The only sure way to find out is to pressurize the system (do a leak down test) and see where the fluid is coming from. Then you'll know what to go after if a repair is required.
WRT the oil leak at the rear of the oil pan, I'd suggest that your oil pan gasket and/or your engine rear main seal itself is leaking.
Bottom line, I wouldn't consider the car unless it gets a clean bill of health from an independent auto mechanic whom you trust and any repairs required are factored into the purchase price. You can mitigate the cost of repairs somewhat if 1) you're mechanically inclined and can do them yourself, and 2) you don't need the vehicle as a daily driver if/when you have to take it off-line for repairs. If this is being sold by a dealer, and they want the sale, then have them get the car repaired by a Subaru-qualified tech to your satisfaction with a 12 MO/12K warranty (Subaru's warranty on parts/labor).
Just a couple of quick thoughts...Let us know what you find out/decide.