You need to find out if the fire or fuel quits and go from there
If your Subie is a newer model (mine is 2015) you have to unlock it with the remote-equipped key, and start it with the same key. Otherwise you can run into the "engine immobilizer" that kicks in if you are not using the correct key with the proximity sensor built in.
That engine needs fuel, compression and spark to start and run. You are missing one of those.
it is most likely your fuel pump
Check this site for information: http://www.troublecodes.net/Subaru/
The reason for a oil spray out of the front differential dipstick in a 1999 Subaru Legacy is because of the cold. While it was -30 the car oil thickened, when the engine started and tried to pull the oil through, pressure was created.The engine was not able to pull the thickened oil in and the pressure pushed the oil out of the dipstick.
I wouldn't have any idea where to start. My recommendation would be to do what I did when my Outback just quit running in my driveway. Call the local garage for a tow truck. This forum doesn't lend itself to the lengthy conversation necessary to narrow in on your problem.
Have vehicle scanned to determine the problem
If you want the same engine look at the drivers side of the engine block for a ID should start with a E eg.EJ22. If you want a different engine well nearly every 4cyl subaru engine can be swapped around 6cyl are larger and may fit. you can fit a ej22 into a brat and a ej22T with a little bit of modification.
the temp sensor opperates the choke flap , and if the sensor is faulty the choke will stay open and make it difficult to start, and on cold mornings some times make it impossible to start
Try holding the "VDC off" button down for 10 seconds. Not sure, but worth a try. I think I might reset when you start up again.
You unplugged the battery and it won't start? What's the problem, maybe no Electrical Circuit? PLUG UP THE BATTERY and try again or get a GOOD BATTERY and try again or check FUSES/RELAYS.
Most 2.5 Subaru's take a little over 4 quarts of oil with filter. Add 4 quarts and start engine. Shut off engine and check dip stick. Make sure oil light goes out. If you have a gauge it should read when you start it.
Classic "air bound". Start engine, leave off rad cap, turn heater all the way up, open plastic vent on opposite side of radiator, and slowly fill with coolant.