I believe the mechanic you may be having trouble with is his pound ability. This is not the pound that knocks everyone into the air, but the one that specifically roots someone into the ground. This pound gives them a debuff that lets them take increased damage from the boss. On Hard or Nightmare, I've seen players get hit for well over 30k damage from his cleave. Being a Sorcerer, I just pull people away and they run back in when it wears off. That being said, there is a much simpler strategy than dancing around to avoid his cleave, and while there is still a lot of movement, it adds a lot more predictability to the fight. My guild runs with 2-3 Ranged depending on who's signed up, 2 healers, and 3-4 melee. We have one RDPS at the north, south, and east ends of the platform, just inside the metal ring. The healers are at the Northeast and Southeast, generally. When the cats spawn, they're instantly CC'd and ignored the entire fight. The melee should stack in the center, and the person with threat should keep Bonethrasher faced West. They will eat his cleave damage, which can be easily healed through if just one person is getting hit. When he goes after the healer, or the ranged, they run slightly forward and turn him roughly 90 degrees so that way if he does his knockback, they don't go flying into an acid pool. Once this is done effectively, healing is quite minimal and it tends to make him pretty easy, but again, that all depends on everyone doing their job properly. I prefer it to just running around in circles though.

You could also just level Armormech and make yourself the 140 Belt/Bracers and avoid the problem entirely.

When my guild started, we generally set a requirement that everyone have a minimum of ~116 level gear. A lot of us farmed HM Flashpoints for Columi and had around half or full 136 by the time we started, minus the weapon and a few other pieces specific to Operations. I would suggest doing Normals only as practice for the Hard Modes, and only if your group does not have a lot of Columi. Loot distribution is not controlled and potentiall not ideal in Normal Operations. They will help you get the basics down, which is important for fights like Bonethrasher, Fabricator, and Soa. Eternity Vault will be the easiest to start with. Besides Soa, the Annihilation Droid is probably the hardest boss in there. Soa can be difficult because of how heavily coordinated your group has to be to deal with the incredible amount of randomness the fight offers, but it is a fun challenge. I recommend going 4/5 EV to start, then work on clearing KP. Karagga himself is only slightly more difficult than Foreman Crusher, and Foreman Crusher is KP's free loot boss. For Fabricator, make sure your group understands how to solve a Tower of Hanoi puzzle.

I raid lead for my guild, and while researching this fight when we initially attempted it, I came across the actual name of the puzzle, which is entirely the key to understanding this fight. http://en.wikipedia.org/wiki/Tower_of_Hanoi The .gif there shoes how to do it when using four blocks, but the game only uses three. We're running with 1 Jug, 1 Sin as Tanks, 2 Merc RDPS, 1 Sin DPS, 1 Sniper DPS, 1 Sorc Healer, 1 Op Healer. The tanks trade off at 4-5 stacks of the debuff. Melee should stand outside of the yellow crossbars when damaging the boss as to not get obliterated by triggering the fire that weakens the boss. When the boss is not weakened, the DPS on the bottom should focus on killing Stun Droids ASAP. We put 1 Merc, 1 Sniper, and the Sorc Healer up top. The healer heals the two DPS solving the puzzle as well as assisting the Operative on the ground. The Sorc makes use of Static Barrier to burst the Mine Droids. Two at a time only. Any more than that and you may need the other healer to help keep you alive. You cannot use the same column consecutively, so we take the boss from North-Mid-South and vice versa. Note that in HM you should not ever use the middle trigger. Whenever the DPS is ready to fire the trigger, make sure the tanks are ready and that nobody is inside the box the boss should be standing in. Fire, zerg the boss until he's not weakened anymore. Get back on droids.