My first impression is the same as Mr. Paul. If you are SURE that the oil level is correct per the owner's manual and markings on the dipstick, and you're getting a ton of oil coming from the crankcase breather hose...
Then I suspect, because of the "oil pressure warning on idle", that someone didn't put the hydraulic lines back together correctly, and that they somehow routed the lines from the oil pump into the crankcase breather hose network.
This would cause a larger than usual flow of oil, because the oil is normally squeezed out into engine bearings. The increased flow rate into the unrestricted breather hoses would certainly cause a drop in oil pressure (and the light to come on at idle). In addition, because during normal operation of the engine, the crankcase gets pressurized by the gasses escaping down the cylinder wall, this would cause the oil to shoot out into the air filter box, as the manufacturer intended.
I normally wouldn't even think this to be the case, because the oil pump supply lines are typically metallic and connect in very specific places, but it may be worth investigation.