Within reason, you could go either way - bare root or potted. As indicated by DouglasPeel, and the reasoning behind it, a plant whose roots are disturbed in the growing season is likely to suffer from shock and be set back a few weeks, before it recovers. But so does shipping a plant and buying a neglected one from garden center, like Lowes. With a plant that is potted, in theory, the roots aren't disturbed. But being taken out of its existing element (light, temp, humidity) may also lead to a little bit of shock. We, as hobbyists, often try to ship pitcher plants and others with the soil it had been planted, so as to minimize root disturbance. But what can't be controlled is the shipping - no light, change in temp & humidity). Either way you look at it, unless a plant is hand-delivered by a friend, there is the potential for at least some setback. And as long as the plant is healthy enough and one's cultivation skills are decent, the plants recover.
There is a general rule of thumb for living critters.... the colder and darker the conditions, the bigger and less colorful they will be. The warmer and well-lit... the smaller and redder / more colorful they will be.
You can use fungicide if you'd like, but that is usually not necessary - particularly if they are exposed to the sun and air. It's terrarium use that runs the strongest risk to mold.
Can you put your pitcher plants outside? That would be the best for them. I have mine set up in buckets, as minibogs, so I can tote them to the attic for winter dormancy and place them outside from spring through fall. And this way I don't have to take them out for a fridge dormancy, either.