Leaking a lot of fluid

I recently drove the car and when I parked I heard a leaking noise. I opened the hood and I saw white smoke coming from the engine block. I looked and a dark brown fluid was leaking into the valley of the engine quickly. I checked the oil level, half way. I checked the coolant: bone dry. which is weird I just filled up three weeks ago. So my question is, could coolant look dark brown and feel oily. Could I just get a coolant leak stopper? Also my front right brake was smoking white.