How serious is a coolant leak on a 1995 Saab 900s...details/history below

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Hi, This car has been great for me for a year but I'm not sure how long it's going to last now. Over the summer the upper coolant hose suddenly blew while driving through Boston. A very good samaritan identified the problem, drove me to autozone where I bought the part, and he fixed it. Then I started noticing periodic, small leaks. I tried some stop leak but it didn't seem to do the trick. Thinking it was the heater hose, I was going to buy the part but I realized the problem is not just when I use the heater. Also, sometimes in the car I also notice that the interior starts to smell like coolant. That could be because I had a container of it in the back, or perhaps it's from leakage in the engine. Finally, when the cold started a couple weeks ago, I started noticing a lot of white exhaust coming from behind my car, especially when stopped at a light. It could be me just exaggerating the amount in my head, thinking that my car is smoking when actually it's a normal amount of exhaust...hard to tell. On the other hand, I know that's a sign of a blown headgasket, and it makes sense if I have a blown headgasket that the interior might smell like coolant from leaks in the engine. Any ideas? Thanks, Tommy