What am I supposed to do now? Is there a way to get the curse client working again? I've googled it but haven't found any useful results. Do I have to uninstall & re-install it from scratch? Has the Curse client been taken permanently offline, meaning that it's no longer viable software? Do I have to install a Twitch client and manage my WoW addons from there? If so, do I have to re-install all my addons from scratch, or will they somehow carry over from Curse to Twitch?
Also note that power leveling is sometimes used to refer to paying someone else to level your character to cap as fast as possible (i.e. they power level for you); a distinction used by Blizzard is to refer to the paid leveling as "power leveling service." This behavior is against Blizzard's Terms of Service. Power leveling yourself, which this article covers, is perfectly acceptable.
Arms: Sharpen Blade - When activated, your next Mortal Strike will deal 15% increased damage and reduce healing taken by 50% for 6 sec. Fury: Battle Trance - You go into a trance causing you to regenerate 3% of your health and generate 5 Rage every 3 sec for 18 sec after using Raging Blow twice in a row on a target. Using Raging Blow on a new target will cancel this effect. Protection: Thunderstruck - Thunder Clap roots all targets for 1 sec. Tuning
Cooking benefits all classes, especially melee and hunters (it is a free source of food). Until higher levels, the benefits it provides are almost exclusively stamina buffs. While more stamina is always nice, cooking is not essential to leveling. Considering the time investment required, if you pick up skinning then cooking would absolutely be a wise skill to level prior to hitting your level cap, as beasts often drop meat useful for skilling up.
Heirlooms are special pieces of armor that level up with your character, so they have stats that are always respectable for your character’s level (up to level 110). Heirlooms that fit the head, shoulder, chest, legs, and back armor slot offer an experience bonus. The total bonus is 45 percent if you have them all. It’s also possible to acquire a ring that adds another 5 percent, but you must win a fishing contest acquire it, and that can take some time.