There are really only two sensors that will stop a subaru EFI engine from firing. They are the crank sensor, and the Cam sensor. These two normally only fail when hot, normally after driving to operating temp and then park it for 10 mins, if it don't start, it's one of these. Pour water ontop them to cool them down while still cranking it, you will be AMAZED when it fires!!! I KNOW this is not your problem, just sprouting!!
I would not say coolant temp sensor at this stage. From what you are saying, I would be looking for spark, injector pulse and fuel pressure. Nail these down and you're halfway there!! You got no Inj pulse, cam or crank, you got no spark, cam or crank, etc etc....
Cheers HTH
Sixpack Subaru