The categories should reflect this, and should not include retail realm categories.
Many of the instances in the game require keys or attunement to enter, or to reach their entrances without needing to go through the lesser dungeons in front of them. Some are easy to obtain. Some are long and difficult quests.
To get it, you must travel to The Altar of Zul in the Hinterlands. Here on top of the temple, you will find two trolls around lvl 50. Kill them and get the [Sacred Mallet] from the corpse of Qiaga the Keeper. Then travel to Jintha'Alor, also in the Hinterlands. On the top of this temple you will find an altar. Stand near the altar, and click the Sacred Mallet to convert it into the Mallet of Zul'Farrak.
Yes, the mallet drops and is usable in a raid.
The method of getting the mallet can be read on Ancient tablets that drop from mobs in Zul'Farrak. The tablet itself serves no other purpose but can be sold to a vendor for a reasonable price.
This attunement was removed in patch 3.0.8. The gong no longer requires an item to use. The mallet is still obtainable as before, but it now becomes a rare quality one-handed mace.
Before entering the Maraudon instance, you will have a choice of entries. You can go into the orange or purple areas, or go straight ahead to the first Kahn. Behind the first Kahn is a small altar. Use the Scepter on the altar create a teleporter. Only one person in the group needs it.
No, the quest items for the staff will not drop in a raid.
Opens shadowforge doors in BRD. Allows you to skip things like the Ring of Law and gain access to the Grim Guzzler bar.
When you enter Blackrock Mountain, you will see an island suspended over the lava by chains. Walk across the chains to get onto the island. Inside the building on the island you will find a tomb. On this tomb stands Franclorn Forgewright who will give you the quest [52D] Dark Iron Legacy.
The catch, he's a ghost and you need to be dead and a ghost yourself to talk to him. The quest requires you to kill Fineous Darkvire and retrieve [Ironfel] from his corpse. Once you have Ironfel, find the statue of Franclorn Forgewright and use the hammer on it.
If you want to kill yourself, for example by jumping into the lava, be sure to unequip your gear so that you can avoid the 10% durability loss.
Enter Dire Maul East from the center courtyard. You will find an imp called Pusillin there. Talk to him and he will run away and stop further on. This will happen about five times. Take your time and clear the mobs along the way. When he's finally cornered you will have to fight him. The key is found on his corpse.
Dire Maul is capped to 5 man, so no raids.
During the fight, Pusillin will sometimes put up a magic reflecting shield. Be careful you don't get hit by your own spells. Wands are not reflected.
Opens the door to Scholomance. Please note that only one member needs to open the door, so you can most likely avoid this costly quest. The door can also be opened by lockpicking or using a [Powerful Seaforium Charge].
A good place to gather the 15 skeletal fragments is Felstone Field where reasonably low level skeleton casters can be found. Eventually you'll end up in Tanaris where you need 15 gold and 2 thorium bars as part of the quest  Fire Plume Forged.
After completing the quest in the Un'Goro Crater, return to the original Scholomance key quest giver. The last part is retrieving [Araj's Scarab] for the head of the key. After all this you will receive the [Skeleton Key].
No, quests cannot be completed in raids.
You'll have to do the quest  All Along the Watchtowers before you can get the Scholomance quest. The Horde also has to do  Scarlet Diversions as a prerequisite. The towers have an elite in them (these are now non-elite since patch 2.3), but you do not have to fight them. Just stand outside the tower facing a side of the doorway and use the flare. You do NOT have to do Alas, Andorhal. Also, attacking Araj the Summoner from the west allows you to pull some of the guards safely.
Yes, the gems and seal drop in a raid. The rest must be done in a regular group.
To enter UBRS, only one person in the party/raid needs to have the Seal. Walk up to the door that separates UBRS from LBRS and it will open. It is not necessary to equip the Seal (Since 3.0.2 the UBRS door is always open).
When you enter Blackrock Mountain, you will see an island suspended over the lava by chains. Walk across the chains to get on the island. When you get all the way down, you will find a high elf Lothos Riftwaker in an alcove. Get the attunement quest from him.
Enter Blackrock Depths (BRD). When you get to the end of the instance, go to the The Black Forge. Beyond it is the swirly entrance to the Molten Core. Next to it on the left side is the [Core Fragment]. DO NOT ENTER the Molten Core before touching the fragment! If you enter the Molten Core and get out again, you'll end up outside next to the Elf, so stay in BRD unless you've done all you want there.
No, BRD is capped to 5 man.
However there is an easy way to get a lot of people attuned without running BRD over and over. Go through the first time with a warlock in your party and have everyone who needs attunement wait outside the BRD portal. After the initial group gets attuned kick two people out the group. Now add two new members to the group, let them enter BRD and get the warlock to summon them. Repeat as needed..
Once you are attuned, there is a shortcut to the MC. In the alcove with the elf, you can talk to the elf and be teleported into the Molten Core. If you have to corpse run, you are still able to talk to the elf and be ported while a ghost.
No, the attunement does not give you a physical item.
The Drakefire Amulet was acquired only after a long series of quests. The lines differ significantly by faction, starting with [60D] Warlord's Command for the Horde, and Dragonkin Menace for the Alliance. As of patch 3.0.2 the quest chain can no longer be completed but the requirement is removed as well.
Obtaning the Onyxia key is a quest line, spanning multiple areas, and two instances. The first quests are not raidable, however, most of the quests starting with [60R] Stormwind Rendezvous for the Alliance are raidable, and a raid is necessary to complete them.
No longer needed to enter Onyxia's Lair. However, if you are not in a raid, the error message will say you need to be in a raid and have the Drakefire Amulet in your inventory.
When you enter Blackrock Mountain, you will see an island suspended over the lava by chains. Get on the chain but walk upwards. Jump off and go right. You can jump on a balcony at the end. In front of you will be the swirly entrance to Upper Blackrock Spire (UBRS).
Enter UBRS and make your way to the end. Kill General Drakkisath and touch the orb behind him to finish your quest.
Yes, everyone can touch the orb.
Once you are branded, a quick way into BWL is touching the orb in the room where the Scarshield Quartermaster hangs out. You don't have to successfully kill Drakkisath, it is possible to use the orb while he is still alive and fighting.
No, the attunement does not give you a physical item.