I went in today to Old Kingdom for first time (OK, halls of stone past brann, and oculus are the only heroics I haven't cleared yet). I found the same things as hachoo, first boss is just simple tank'n'spank, for second boss keep team 20 yards away and the fireballs shouldn't hit them first pass, lust quickly and its not too bad.

For third boss I tried kiting her away to the doorway into the area, she resets however so they fixed that way of getting the achievement I was able to get the achievement (kill her w/o killing any adds) but it took a lot of spam healing on my tank, she was hitting him for 14k a melee swing. Not too bad though, just remember to move out of the thunderstorms - I keep my DPS near the waterfall area and just have them strafe left/right if a tstorm appears, otherwise just keep DPSing/healing. If you have a warrior tank you can disarm her and make her enrage a joke

For the "extra" boss, I wiped once trying to run around kiting between shrooms. Screw that. Second time I just consecrated a bunch of shrooms, lusted, and went all out on her. My guys had like 200% dmg buff so he went down in 30 secs or less, had to run once to a second shroom but other than that, I would just treat it as a burn fight and not focus on the shrooms too much.

I absolutely detest the last boss, I tried a few times to get the achievement (kill him in 3 minutes or less), just wasn't happening. I think I would have to respec my pally to ret and my resto shaman to elemental to get it. If you have high enough DPS (tank+4DPS) you may be able to do a quick burn, some comments I read say that you lust at start, put on slow/CoT on boss and keep burning when he is casting insanity, and if you get him to 25% before he finishes first cast he will start a second cast and you have 5-6 seconds to kill him (ie no insanity!). I wasn't even close to do this DPS-wise, I think he was at 60% and insanity went off, all my DPS eventually died and I took the boss from 50-0% just with my tank/healer through 2 insanitys (lol). It sucked, I doubt i will ever come back to this boss.

Gonna work on halls of stone and oculus before my accounts expire, so I can at least have full heroic clears.