For the record, the adds are not meant to be tanked by actual tanks.
Rage fixates on a random raid member, but they're weak and CCable. Strength has a normal aggro table, but a ranged should have the threat, due to constant PBAOE. Courage fixates on a far tank, but can only be attacked from behind.
So I'd put melee on Courage, Ranged on Strength, and everyone on Rage when those are dead. THEN the bosses.
EDIT: note: I refuse to do LFR because I can't get in with a tank spec even when queued with a healer. I suppose I can farm DPS gear at some point. And no, I'm not going to DPS in tank spec. I'm not that desparate.
2. it is possible to aggro one but if it takes that long for it to die then the group is bad. (think of their fixate as if the one that's fixated just used a super insane taunt)