Even bubbling is ok for a short time. Water boils at 212, give or take for altitude and impurities, anti freeze increases that boiling point. your gauge is a good indication of how hot it was. A better way to cool the engine is to turn the heater on full blast on hot to help strip the heat from the coolant, occasionally starting the motor to move the coolant in/out of the heater core. Any water poured on a hot on a engine block causes shock and can facilitate a head, block, or gasket crack.
All that being said..a whistling sound is steam escaping, somewhere there is a leak, maybe on the radiator, or the head gasket, or around a freeze plug, or it might be at the overflow. check the engine oil, if it is white, water has made its way into it, usually from the head gasket, but it can also make its way through a crack between the water jacket and the block. White motor oil is a bad sign.
One other thing you can do is go to the auto store, and get a bottle of UV dye (they come with a UV pen light), put it in the coolant and run it, and in a dark garage start looking for the tell tail UV dye around the head and block.
Its kinda hard to say what happened, but a few NO NO's happened with pouring water on the engine. that whistle sound should be found to find out if its a pin hole some where, or a head gasket. (on a bright note, i have never heard of a failed head gasket whistling, its usually signified by a pour running motor)
your prestone 50/50 is ok to use, no harm