As far as the Detonating Lashers go, of course that's on your DPS to aoe until the stop is called, then do whatever you can to immobilize them for a few seconds. We use frost nova usually, but if a mage isn't available, try Shockwaves/War Stomps/Desecrated Ground effects. This should give your softer raid members time to fan out.
Sounds like the Conservators are not a major issue for you, good work avoiding the guy with the skull on his head.
The three stooges are the critical point for tanks. The way we're handling it right now seems to work very well, and I would highly recommend it to anyone having trouble with them. We have a DK tank the Snaplasher, and myself as a warrior on the Water Spirit and the Stormlasher.
1) Ancient Water Spirit: This guy likes to do a long range rush on the person IN his range that is furthest from him. His cast, Rushing Surge or Surge or something like that, is about a 2.5 second cast. He's stunnable, so that should take care of his random movement. I have no trouble keeping him stationary without outside help, i.e. with my own stuns (including War Stomp sometimes) Concussive Blow and Shockwave. If you're falling behind on stuns, assign 1 or 2 rogues/pallies to help out. He hits like a mage with his melee, so it's not critical, just helps you keep aggro since you might lose it on one of his 40 yard forays into the raid.
2) Storm Lasher: Seems to be mostly a caster mob, still melees, but very lightly. We have our rogues on him for stuns/interupts since the Ancient Water Spirit is locked down by a Prot Warrior. This helps alleviate some strain on healers due to lightning attacks of various nature.
3) Snaplasher: This guy... Put your DK on him for Chains of Ice root/snare when his health gets low. He does 1% more damage for every 1% health that he loses, not to mention hits pretty hard right outta the gate. Allegedly he also loses 1% of his movement speed for every 1% health that he loses, but to be honest, the mechanics of this aspect seem flawed or bugged. We aren't taking any chances with him. This means he'll be untankable as he gets below about 30%, he can one shot tanks.
Warrior tank should thunderclap as they spawn to grab them all, DK should peel off the Snaplasher as soon as he/she can. We burn the Water Spirit and the Storm Lasher to 5-10% as quickly as possible, then switch all DPS to the Snaplasher. This cements the DK tank's aggro on the Snaplasher, which, unlike the other two, is fairly crucial. It also allows the DK to actually tank him until it's time to kill it. We burn the Snaplasher straight to 0%, making sure the Chains of Ice stay on CD after 30-40% health. With all dps focused on Snaplasher, it should go down before it can recover from being rooted. When the Snaplasher dies, make sure to immediately switch all dps back to the other two and finish the last 5-10%.
Good luck to you, hope this helps.