The crafting system that isn't tied to an adventure pack is the Cannith crafting, which is a much more general system. You break down any old random loot you get in quests, then use the ingredients that gives you to build new items. Unlike other crafting systems, you need to level up in Cannith crafting, which can take a while, and at this point is probably not worth a major investment, as random loot is just generally better at the moment.
There aren't any other professions or anything like that, just questing and raiding. If you're looking to become a blacksmith... you've found the wrong game. :P