Ah Brematt
I was diagnosed at birth (because of salty skin) and so had physio every day. I have worse digestion problems than lung, although as i get older the digestion has smoothed out and i am more aware of how to eat and drink to minimise enzymes for peak nutrition - just listening to the body.
My bigest hint for all CF parents is throw away the TV and playstation, xbox etc.
Your kids really won't miss out on that much, you will spend so much more quality time with them, esp if you are concrened about life expectancy, and they will go outside and exercise which it the most important thing! I should know - Grew up on a farm and no TV until I was 15 - and that's when my hospitalisations started! Lack of activity and alcohol consumption are bad for me, doesn't mean i don't watch tv and drink, but i recognise the ill effects.
I work in a limited exercise environment, on a boat, but at least the salt air is good for me! I try to do breathing exercises etc, make the best of your child's environment, get him to play heaps of sports. I found that if I played lots of sports I could get away with less physio, so that hour of isolation became a social hour and sweat and team/morale building, looking back now that is!
Best of luck.