Replace the Ony Blood trinket with Glyph of Indomitability and get rid of those parry gems. Even if it were a good idea to gem avoidance stats (which it isn't), Dodge is point for point in every way superior by a fairly substantial margin.
Effective Health is a concept you should make yourself familiar with. It's a function of your health and armor. The math isn't important; what IS important is the fact that after your defense is capped, Stamina and Armor are your two most important stats, because they allow you to eat more sustained hits before dying and thus make you easier to heal. Raw avoidance stats do not (this is not to say Dodge is necessarily bad, but it's not as good as armor for a bonus stat).
Similarly, Expertise isn't going to be a huge deal for you unless you tank as Blood; I don't play a DK but if I'm not mistaken both Frost and Unholy have a lot of straight-up spells in their rotations, for which Expertise is irrelevant. Again, this is not to say Expertise is BAD for a tank; it's just that you'd probably benefit more from stacking more avoidance. As a general rule, you shouldn't gem/enchant for threat, because tanks have such a huge inherent threat lead on DPS now if you lose aggro it is almost certainly a gear differential or rotation issue. YMMV and I'm sure someone will pipe in to disagree, but you're just better off with more effective health for now.
Heavy Borean armor kit for your gloves, enchant your chest (275 health) and cloak (225 armor). Buy the triumph tanking ring for your second slot after you get the trinket, and go get Tyrannical Beheader or Mourning Malice. First Frost Badges would go to the belt or the cape unless you're hot for T10; in that case I'd say go T10 gloves and shoulders to get your 2-piece as fast as possible and then go belt and cape, because they are both crazy good. If you are rich get the Primo Sar tanking boots because they rule, but that's all long term.
For now you should ideally be shooting for 35k unbuffed, which is very attainable for all classes. Raid-buffing to 40k in a ten-man is a good mile marker because it will allow you to survive two consecutive hits in additional to unavoidable ambient damage from nearly every boss you'll be expected to tank, which is more than enough time for somebody to drop a big heal on you.
This http://www.wowarmory.com/character-talents.xml?r=Korgath&cn=Shockazooloo&group=1 is a spec a see being thrown around a lot in Raid tanking for DKs.
There is no way anybody in this life or the next is going to convince me that Morbidity is better for raid tanking than 10% more slow on icy touch.