Aiding the Accord: Sniffenseeking

On my alts, I accepted the popup quest The Land Beneath, picked up Aiding the Accord: Sniffenseeking and flew straight to [npc=201426] at /way Zaralek Cavern:Dragon Isles 55.64 57.47.
He had one map available and I was able to complete the "Dig completed with Myrrit" part. There's no need to do any extra quests or purchases to complete this.

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• Brand New Digs: In the cave with the box with a red glow & green cloud, sniff out [item=204867] next to the box, dig below the green cloud and put [npc=201426] on the pressure plate to remove the red barrier from the box. Jump down and open the Treasure Chest.
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• Flapping and Screaming: In the cave with the crystals. Pick up the [object=402580]. Use [spell=411283] to capture a [npc=205417]. Stand close to a crystal so the captured bat can shatter it. Repeat until you find the [item=205969] (mine was at 54.99, 48.94). Unlock the [object=402595].
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• Element Whispers: Go right and use [npc=201426] to dig up cracked tablets in front of each pilar. On each tablet you'll find a cardinal direction and an element mentioned. Go back and now take the left path. West(left) of the [npc=204800]: Choose earth, North(behind) of the [npc=204800]: Choose fire, East(right) of the [npc=204800]: Choose air, South(in front of) of the [npc=204800]: Choose water. Talk to [npc=204800]: "Can you check to see if my pattern is right?". Kill [npc=204800]. Loot [item=205689], jump down and unlock [object=401296].
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• Those Rascally Worms: Talk to [npc=204587] to make a deal. Use [npc=201426] to dig up [npc=203850] ("Phew, that's worm-stink!") and [object=398116] ("I smell something un-wormlike") to collect 6 [item=202180]. Talk to [npc=205267] to feed it. Click on the basket [npc=205267] was on to collect [object=401242].
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• Sneak and Sniff: In the cave with bats & worms you just need to go pick up the [item=205412]. I'm not sure if something I did made it spawn, but it was certainly easy to miss. No need to kill the bats nor worms to my knowledge.
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• Thieving Critters: Go to the room with the [object=400987]. [spell=400132] at the entrance of the left path. Wait until the orange cloud moves over you and [spell=400143] up [npc=204432]. Kill it to receive the first key. Follow the right path and destroy [npc=204439] to spawn [npc=204435]. Kill it to get the second key. Use the [item=205185] and [item=205186] to unlock [object=400987].
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• Living Statue: Kill both [npc=201871]. Pick up the Light Etched Key and restore it by putting it on the Etched Receiver with the small orb on it. The other 3 keys can be found by sniffing & digging below stone piles around the cave. Once the 4 keys are restored, click the statue and kill [npc=204419]. Use the [item=205938] to open the [object=402532].
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• Liars in Light: Stand on the pressure plate next to the Tauren Statue. Talk to the Tauren Statue and select "Choose this statue as telling the truth." Kill the [npc=204430] and loot the [item=205202]. Use it to open the [object=402216].
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• Liars of Spirit: [spell=400130] on the pressure plate. Talk to the Regal Statue and select "Choose this statue as telling the truth.". Kill [npc=205540] and loot the [item=205990]. Use it to open the [object=402437].
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• Vertical Anomaly: Kill the adds. Use [spell=400132] and [spell=400143] to destroy [npc=205559] and [npc=205563]. [spell=400130] on the pressure plate. Enter the central bubble to swim to the moving bubble to swim to the bubble containing the [object=397993]. Loot the [object=397993] and use the [item=203655] to open the [object=401295].
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• Scratch and Sniff: [spell=400131] until [npc=201426] says: "I smell something briny over here..." (Mine was at 54.58, 51.25). [spell=400132] and [spell=400143]. Kill and loot [npc=201747]. Use the [item=205277] to open the [object=401310].
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• Successful Interventions: Drink the [object=402597] on the table. Talk to [npc=205080]. "Ask about Ralph." to [npc=205088] until you find the one that says "I'm Ralph. Either ye believe me, or ye don't." Then "Point out that this is Ralph to Mr. Sunflower.". Loot [object=402149] from the table in the corner.
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• Your Weight in Gold: In the cave with gold and pressure plates, sniff out [npc=205330] and let him use [spell=411045] while you're on a pressure plate to put [npc=205334] on the plate (be sure to move away once the golden pool is showing on the plate). I think you only need 3 pressure plates pressed. You can put [npc=201426] on one, stand yourself on another and use aforementioned technique for the third. (I used the technique on 3 plates when I noticed the door was already open).
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• The Living Drill: Use [spell=400132] and [spell=400143] below an orange cloud to spawn and kill [npc=205613] 3 times. Kill [npc=204434] to loot [item=205941]. Use [spell=400131] close to the pool to [spell=400143] up the [object=402534] ([npc=201426] should say "I smell something un-wormlike"). Loot.
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• Making Scents: DPS [npc=203606] until it's immune. Use Smell and read the text. Click the orb matching the message ("Is that burned charcoal I smell" = fire, "why did that orb start smelling like worms?" = earth, "Oh wow, it smells just like lightning! = air"). DPS [npc=203606] until dead. Loot.
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• Heart of Iron: Kill [npc=204426] to get the [item=205939]. Use [spell=400131] to find "Wait! There's LESS burning smell here!". Use [spell=400132] and [spell=400143] to dig up [object=402533]. [spell=400130] and open [object=402533].
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• Frostfire Finesse: In the cave with the Fire Charge and the Frost Charge, click the Fire charge and put [npc=201426] on the Pressure plate of the Frost Charge to pick up the [item=206001]. If needed click the Neutralizing Charge to remove any remaining [spell=411698]. After that click the Frost Charge and and put [npc=201426] on the Pressure plate of the Fire Charge to pick up the [item=206002]. Once that's done, use [spell=411729] to combine the keys to the [item=206000] and open the Frostfire Cache.
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I get to the cave, it has a locked treasure chest. I sniffed and found the "Metal key" but when I use it on the chest, I get the text "you can't do that yet" - sniffed all over the room, nothing else, tried tunneling under the chest, no luck, tried dropping the quest several times...

Drop Merrit on the metal circle on the ground. In doing so, a bubble above the dirt pile with bubbles/water will appear with a chest containing the key. Get in the bubble in the center where the locked chest is - swim and position yourself towards the direction of the bubble containing the key. Make sure to stay within the bubble still. Time for the other bubble that goes around the room so it aligns to the top most bubble where the key is located so you can "swim" across to get the key. Hope this makes sense.