99 Subaru Forester Overheating

My 1999 Subaru Forester has been overheating for quite some time, and the heater doesn't usually work. I've had the radiator flushed and the thermostat replaced recently, but neither helped. Yesterday it overheated to the point where smoke was coming from the engine. When I opened the hood, I noticed that coolant had splashed out from somewhere and was sitting in small puddles on top of the engine. Also, when I took off the radiator cap, there was no more coolant inside and there's brown, rust-like liquid around the bottom of the cap; however, the overflow reservoir was filled way past the fill line, which has never been the case. The engine has been hesitating for a while too, but I have no idea if that's related.