This has got to be a hard time for you, and understandably so. That being said - you've come to this forum for information, and that's the first step to really understanding. Now to answer your questions. The median age for survival for a CFer is I believe 36. But it is different for everyone. There are CFers in their 30's, 40's, 50's and even 60s. People who have lung transplants, can also be around for a very long time afterwards. Everything depends on your gene mutations, your environment, how active you are, how diligent you are with your treatments. I'm sure its scary finding out that he has to do all these treatments, all these medications, etc. But it will get easier with time. What advice I can offer, is try not to treat him differently. Don't treat him like a guy who has a disease, but rather just a guy who has a small different thing about him. I'm sure now that you know about his CF, he will tell you about all the ins and outs of CF, and I'm sure there are a lot of people who will come on here and tell you as well. Because you're 18 though, I would also suggest posting this in the adults section - you may get more of a respnose there as well, as the only people that usually come on the teen section are teens. You may get more of an adult response from the adult section.
Good luck!