Check to see if the oil is mixing with coolant and vice versa. That is usually the best sign of a blown HG. Also, check the compression and if there are two adjacent cylinders with bad compression, it is usually the head gasket. The leak is pretty scary though. I had one of those and had to do my headgasket. I didn't want to pay out the ass, so I borrowed my GF's car and started tearing mine apart. It isn't that hard to replace the HG and it is a great learning experience. I would check to make sure that it is in fact your headgasket before you jump to any conclusions, though.

And also, the firing problems may be due to coolant leaking into the cylinders and fouling the spark plugs. I just recommend getting a professional opinion and then going from there.