FYI: If you’re returning to WoW after an extended absence prior to patch 5.0.1, it’s possible that you’ll have more than the maximum pet limit and/or more than 3 of a kind. However, this will be the only time that you’re allowed to surpass these limits. You will have to pare down your collection, eliminating your duplicates, in order to add new pets.
There is an Action Bar at bottom of the User interface. Each class starts with some skills. Every few levels, you will unlock new skills specific to your character class, these can be learned from your Class trainer. You will be introduced to one of these NPCs during one of the first few quests you complete in your starting zone, but they can also be found in many towns and each of your Faction's cities.
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In the end, while it may be a huge cop-out, it really does come down to personal preference. Some people will simply not be able to handle the huge downtime between pulls, not being able to buy a new skill rank because you spent all your money on food and drinks (mages were popular for a reason back then), the very slow pace of leveling, and a whole lot more frustrations and not user-friendly features. On the other hand, the experience really is significantly different enough from modern WoW that it does feel enough like a "new" game, or at least a new and different expansion. An expansion that has many more differences than the last 3 or so, something that's both new and old and familiar. And, yes, it also offers massive quantities of nostalgia for those of us that played Vanilla, but what's so wrong about that?
Keep in mind that these quests are optional, and are not necessary to continue leveling and capturing companions. They are also account-wide, so if you complete the quest chain on one character, you will not be able to complete it again on another. However, any progress that you've made will be saved and you can pick up where you left off in the quest chain on another character. The dailies that you've unlocked will also be accessible by all your toons.
I'm not all that hardcore on "Classic", I want to relive the old zones and the old world and it seems like most people I'm taking to is feeling the same. We would prefer to have quality of life improvements regardless of them actually being in the game at in 1.12.2 or not. Like the "Automatic Quest Tracking" to actually track it properly without you having to actually trigger progress in the quest for it to show up would make perfect sense. It's no real need to make such a thing behave nonsensical just because it's "authentic".
Unlocking the Lightforged will require you to complete the aforementioned Argus storylines and earn the “You Are Now Prepared” achievement. In addition, you’ll have to earn Exalted status with the Army of Light. As with the Argussian Reach, this one could take a couple of weeks, as it is time-gated. However, the main story quests should help you at least reach Friendly status with the Army of Light.