First rule of DK tanking: Until you're ready for Naxx at LEAST, you're gonna feel like a sponge. As a DK tank myself I went through it, especially after the latest patch.
Talents: One thing I'd give up is RP Mastery. You're not gonna generate enough RP to need the extra room, and you definitely shouldn't hoard it until you do, so those two points can go into Deathchill and Morbidity. Morbidity, because the faster you burn through fights, the faster you'll want your DnD up. If your DPS is up to snuff, you'll need that extra fast cooldown on it. Deathchill serves two purposes. On the initial pull, you frontload crazy aggro with the AoE crit it causes when combined with Howling Blast, and if your DPS is also just getting into Heroics, you'll want the ability to help end fights with the extra AoE damage from - you guessed it - a deathchilled Howling Blast. Chill of the Grave is another talent I don't use, and those two points should go into Lichborne for the fear/stun breaker, and either Hungering Cold for better mob control or Acclimation (1/3) for the added, if slight, mitigation bonus.
Glyphs: Definitely trade out Icy Touch for Howling Blast. You'll build plenty of RP witout it despite frost spec being "RP starved" and it makes things much more easy to deal with. Otherwise, you're good there too.
Rotation (post glyph/talent switchout):
Initial pull - DnD, DC'd Howling Blast, Blood Boil. IBF ASAP, and Rune Strike as available.
Runes cooled down - HB, Ob, Blood Strike x2.
If stuff's still alive - Obx3
Repeat step 2 and three until you're looting.
Initial Pull for bosses:
DC'd HB, OB, BS x2. IBF / RS as available.
Ob x3. Repeat these two rotations as necessary until you're looting.
If there's adds to consider, HB will pick them up, no worries. Just hope you've got a great healer, and have the DPS burn the adds down as fast as they can.
I'd love to help, but you're saved in your DPS set lol. Blinded by that, the best I can say is that if you're still working on getting geared to raid in your tank stuff, farm regular ToC (the new 5man) until you're ready to go. The trinket dropped by the black knight, specifically, is one of the best tank trinkets you can get pre-naxx. +127 stamina, and the 7k armor proc isn't horrible. Currently, I use that, and Essence of Gossamer from Hadronox in Heroic Azjol'nerub. Unless you're a maxed JC, that combination can't be beat pre-naxx.
Good luck, and happy tanking!
PS: The squishy feeling really does go away when you're just about ready for 10man Naxx/OS. I promise!
...Thoughts of a philosophical Death Knight...
If death is the inevitable end of life, is life the inevitable end of undeath?