DPS, progressing story, level up

[OlyverW]

Yes you can switch to other classes and work on other things while you wait for a queue when the commence notifcation pops it will tell you that you need to change your class to what you registered for the dungeon with

edit: since that was already mentioned I will also add that make sure you don't have an enemies aggro if you do you will not be able to switch until you lose it