I'm not crazy. My mother had me tested.
How many adventure packs are used at one time, and do you have to use the new characters that come with them?
The adventure packs for a single campaign. You take a group of characters through them all starting with adventure 1. Your characters will level up during the campaign. You add cards from each pack when you start it. The rules for removing cards are on the adventure path card included in the main box.