DS' is still a teen, but we've always had an infection disease specialist as his primary CF physician then we have a local pediatrician who handles his local needs. One of my friends had a double lung transplant 12 years ago and had has a family practice doctor in town who works well with his cf team in the City.
My CF doctor is my primary care for everything. My insurance wants me to have a regular PCP but I never use him. Everything goes straight to my CF doctor first since my CF is the main cause for everything and needs to be coordinated with my CF meds anyways.
Technically, no. My PCP is at a family health center. I can go to her for non-CF things. I've been to her to get antidepressants (which now I go to my CF doctor for because of weird interactions with CF meds...), for unexplained pain in my side (which she sent me to the ER for and was a side effect of a pulmonary embolism, so therefore a CF thing), an exacerbation when I couldn't get into CF (wherein she prescribed me a Z-Pack and my CF team almost had a coronary and put me on IVs...), and a couple other random things. She's perfectly nice, but I don't really find her useful because she doesn't have a good understanding of CF. Even when I need fluconazole, I just call my CF clinic because it's nearly always due to something they put me on. So, my pulm ends up being my PCP, which I think is pretty much par for the course. He refers me to psychiatry, gyn, etc.
I see my CF doctor mostly. However, I have a PCP at my local hospital for non-CF related things such as what that strange looking spot on my skin, and so fourth. My PCP will not hesitate to suggest that I go to my CF clinic if she in anyway thinks it could be related to my CF.