I finished the story missions in the CBT. i got alot of EXP boosters from them. MOST OF THE MISSIONS ARE ONLY CUTSCENES(true).. Its a little heart breaking toward the end of episode 1 but incredible. It helped that i unlocked and completed all the expeditions first though. the story follows the expeditions in terms of setting. after that there are a few surprises toward the end plot wise. If i have to complete them again for OBT and full release i will each time because of the rewards. towards the end of the episode 1 you fight more frequently @Guilrel. however i am not sure about the other episodes. i would level up by completing expeditions back to back only stopping to join urgent quests because each expedition gives you a exp ticket to level up quickly. completing expeditions also unlocks more areas. after unlocking hard mode for most content i started the story and was not disappointed. only when i died and had to restart a 30 min story mission ALL OVER AGAIN.