Re: Coolant in exhaust (leaking head gasket?)
Could be that; but prolly not. FAR more likely, the head is cracked some way or other. Prolly in the exh port, since if it was in the cyl (either the gasket or a crack there), it would fill the cyl with coolant and "hydro lock" the motor, and you'd have a bent rod or broken piston or something MUCH worse than just some coolant in the exhaust.
Numquam ponenda est pluralitas sine necessitate.
— William of Ockham, c. 1330 AD, from Quaestiones et decisiones in quattuor libros Sententiarum Petri Lombardi
Roughly paraphrased into modern English, and applied to figuring out what's wrong with your car:
The simplest explanation that fits all the facts is probably the right one.