a) I don't get your point, you haven't stepped into raiding yet (at least with your warrior) and overgear heroics. Aggro in heroics shouldn't be your first concern, all trash is stunnable and you can always use Recklessness or Retalation on a Dungeon Bosspull to smooth things out. And even if the boss turns around and hit those overeager melee once a taunt will regulary fix it.
b) Changing only one item to dodge over parry or vice versa might not change a thing, but swapping from 20% parry + 10% dodge to 15% parry + 15% dodge should net you 0.5% or even avoidance due to dimnishing returns.
c) You can't compare trinkets like this. Throngus yields x fix avoidance and also adds a huge amount of avoidance on a rather short cooldown that you should really take into consideration and redo the math.
d) Against your statement you recently reforged for expertise, why is that? And topping the meters.. with the survival hunters ceasing and Howling Blast nerfed to the ground there are not many aoe dps left that can keep up with Blood & Thunder/cleavespam.