Sean--about lifespan post-transplant. There is no inherent limit in how long we can live after transplant, like Joanne says. There are some statistics on survival, but comprehensive data is hard to find. What I've found recently. For all lung diseases, the odds of surviving 5 years post-transplant is around 45-50%. BUT for CF patients, some studies have shown the odds to be around 65-70% for 5 years. Perhaps because we're younger, perhaps because we know how to take care of ourselves? It's still not known.
So when people get to the end of their rope, CF lung-wise, it is a really good gamble, in my opinion. Because in addition to the odds of living longer, you get to feel better than the last couple years when your CF lungs just sucked. For me-no nebs, vests, or anything--just feelin' groovy.
A little more about post-transplant medical stuff, if you're interested. Mainly, it's about balancing lots of competing factors and getting lucky. Immunosuppression is necessary to prevent acute and chronic rejection of the new lungs. But immunosuppression is tricky for several reasons. First, the immuno drugs have strong side effects--we all know prednisone sucks; other immuno's can hurt your kidneys or cause other problems. Over time, other organs in your body will feel the effects.
Second, by suppressing the immune system, we become vulnerable to other infections, both familiar and strange. For example, I still have pseudo in my sinuses, and sometimes it infects my lungs and I need antibiotics just like before (but now they actually clear the crap from my lungs!). I've also had a weird fungal infection in the lungs, too, and I'm sure if you talk to other transplantees they will tell you some interesting infectious stories.
Third, immunosuppression is not an exact science. Not everything works the same for every person. And each transplant center has variations on which drugs and how much of them to use. This is not because doctors are idiots (in this case), but because it is hard to standardize dosing and do good randomized studies, when there are so few people with such different issues, and nobody, including myself, would want to mess with their own delicately balanced drug levels for a study. Not to say these studies will never happen, just that it is going to take a while, and they won't be crystal clear.
Last, there really is a certain amount of luck involved. No one can predict who will get acute rejection, who will get chronic rejection, who will have kidney damage, or who will end up with which new and wonderful bugs. Most of us get a combination of these, and just deal with them as they come.