Yeah, once you queued up you can do "whatever" you want and go whereever you like.

However, you cannot Change the party setup - Inviting or dismissing party members will abandon the queue and you have to re-queue. You can progress in other quests but cannot attend solo duties. If you are in a cutscene when the duty finder pops, you have to finish / abandon the cutscene in order to accept the invite (you have 40 seconds to do so) or you will be withdrawn and have to queue again.