Coolant Smell in vents and burning Tranny Fluid

I have a 99 Sable LS Wagon With a 3.0l V6 With 155,000 miles. While on the highway I noticed Smoke seeping from the engine compartment at that time the rpm's also climbed to about 3500. Once the car was off and cooled down I checked and noticed that there was tranny fluid all over the top of the tranny. It must have hit the exhaust and started burning off... it looks like some sort of pressure release valve at the top of the Tranny near the shift linkage area. Any Ideas as to what happened. This was yesterday.. but even on the long drive back home the car was fine. Secondly I can smell coolant from the vents when the heat is on.. Yet I cannot see any coolant leaks nor do I lose coolant level. There is also no coolant leaking into the car as my first thought was the heater core. Any help would be appreciated. Unfortunately the service engine light did not come on to help shed some light on this either.

I have since posted a picture.. the red circle is where i have found fluid sitting.. and one of those 3 Red X's is the valve.. i believe it is the top one. At least it looks to be some sort of pressure release valve. The others are part of the linkage.