Through out the game, the quest log will be capped to 20 many times. The guide makes use of maximizing the total amount of quests you can accept at once. Because of this it is important to follow the guide exactly and only accept quests if the guide tells you to so you won't run into issues not being able to accept a quest. If you do accept a quest that is not listed in the guide, write it down because you may need to abandon it in order to keep following the guide if your quest log is full.
You can opt in for the beta at the official site. When the beta launches on May 15, players who’ve gotten in will be able to play all the way from from level one to 30. WoW game director Ion Hazzikostas tells us that the beta will be “uncharacteristically small compared to our expansions,” in part to ensure that the focus is on the proper launch this August.
Workaround as a player is simply to skip forward past that step in the guide, at which point it has steps for the other quests. I'm still on Bleakrock as that character, so I don't know if a duplicate "begin the evacuation" step exists after you've found all the missing people. In either case, just don't talk to Captain Rana about evacuating until you've completed all the other main/sidequests on Bleakrock, which are listed at the UESP link above.