Well you may slowly acclimate them to the new light. This is how you're supposed to do it but honestly, I never do. I just take the new plant and put it right in with rest in as bright a position as possible. The leaves will redden (not brown dry burning) and begin to look "terrible" and the pitchers which were on the plant when it arrived usually die off rather quickly. Sounds bad but this is actually quite alright (so long as your humidity is high) because this means the plants are responding to the light and only the old "useless" leaves are being harmed, not the new growth which will be healthier and stiffer not soft and floppy. The new pitchers will show how they like the light when they begin to form on the new growth as well sometimes you can get the pitchers as big or bigger than the leaf they're growing on!
Yes, you should change your fluorescent tubes every 6-8 months (I just write the month on one of the tubes and when I change them I change them all at once). Power compacts/compact fluorescents can go longer and metal halides a year or so. I just replaced my 400W metal halide (ouch! -$) but I'm looking forward to the new pitchers as all my plants in that chamber began making smaller and smaller pitchers over the last few months and nothing else environmentally has changed.