[Simpson]

Here is my Armory Link.

I hit 80 two weeks ago and I've begun off-tanking 10man Naxx for my guild. While I'm still trying to obtain pre-Naxx gear upgrades, I have a few questions about how I should deal with new gear.

As you can tell from the armory page, I've stacked mostly 8 dodge rating and 12 stamina purple gems. I feel like I'm making the wrong decision, but I don't know what I should be doing. Here was my initial reasoning and please correct me where I'm off.

From what I understand, dodge rating will give more per point avoidance than parry rating. Even with diminishing returns, it is still more effective to stack dodge over parry when choosing gems.

At the same token, I figured more avoidance would do little with a low health pool, so I thought the purple gems were perfect, but now every time I look at them I feel like they're horrible.

Here are my base stats:

Defense: 552
Dodge: 22.38%
Parry: 15.93%
Armor: 27,485
HP (in Blood spec): 30,163

Of those stats, gems are providing:
48 Dodge Rating
8 Defense Rating
116 Stamina

39.3 Dodge Rating is equivalent to 1% of Dodge, so 1.22% of my Dodge is coming from gems

~11.55 HP is gained per point in stamina, so roughly 1,339 HP is coming from gems.

First off, I feel as though my avoidance is very low. Am I correct in that feeling?

Second, how should I be geming my gear? I understand the mechanics behind expertise and hit, and I know I lack both stats currently but I felt as though survivability was more important than TPS, so I've intentionally neglected those stats. Am I wrong in doing so?

I am very close to upgrading Ziggurat Imprinted Chestguard with Heroes' Scourgeborne Chestguard (2 Emblems Away) as well as grinding Kirin Tor reputation in order to upgrade Daunting Handguards to Fireproven Gauntlets.

Please advise on how I should proceed with gems for my gear, and what kind of avoidance numbers I should be looking at to be main tank in 10man Naxx.