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. 

Hey folks! I’ve got a small update here to help quell some of the rumors and let you know where we are at for WoW Classic. We recently began a phase of internal employee alpha testing. The new build data that many of you have been discussing over the last few days is simply part of this process. Phases like this allow us to test out the game content along with other functionality that will be used in the live game, like logging in through the Blizzard 175 App.
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.
WoW: Classic is scheduled for August 27 (technically August 26 if you're in the Americas). The soonest that you can play it is starting in May, during Blizzard's scheduled stress tests. To opt-in you must have an active subscription on your account. If you do, go to Account Management and select the Wow Classic beta. Keep in mind, there will be level caps during the test. The schedule is as follows:

The original World of Warcraft was released in 2004, and World of Warcraft Classic aims to recreate the state of the MMORPG before its first expansion, The Burning Crusade, was rolled out in January 2007. Previously, players looking for a “vanilla” version of the game were only able to experience it on custom servers such as Nostalrius, which Blizzard shut down in 2016 to protect its intellectual property.

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.

Occasionally it's also been proposed to re-randomize all the gear. We didn't have best in slot lists back then. People weren't starting out as a fresh level 1 character with a complete list of which dungeons to run at 60 in order to gear as quickly and efficiently as possible. Now, all that data is available. If gear were re-randomized then all of those lists would become useless and thing would be close to how they were. Which is a more important part of the "vanilla experience?" the fact that item X from boss Y has exactly Z stats on it, or the voyage of discovery? Personally I think that voyage is way more important. Do you remember how many points of which stat on the ring or whatever that Darkmaster Gandling drops? I don't. Would it kill your experience if the BiS for every class were in a different dungeon so people had to actually play to figure it out rather than simply consult a spreadsheet? I don't think it would. For that matter, it probably wouldn't be a bad idea to handle it intelligently so that the better gear is in later dungeons. I remember there because some weird cases where level 40ish gear was better than anything that dropped in level 60 dungeons.