The DK DPS Frost Spec has recently become not just viable, but the best single target DPS spec for the Death Knight. That being said there are some things to note about choosing this over other specs. Pertaining to a raid, Frost brings in a 20% melee haste buff. Not a bad buff, however if you have more casters, having the 13% magic debuff on targets is better. If you are in a static raid that already has an unholy DK, then going Frost wouldn’t be an issue.
Frost DPS is Dual-Wield spec, if you want to use a 2 hander, go unholy or blood. Frost has all the dual wield talents and brings nothing to the 2h weapons. The current accepted spec is 0/52/15 with 4 points left to play with.
The stats you want to go for with Frost are similar to unholy and blood with 1 huge difference. Besides Hit, you will want to cap Expertise first thing. This is crucial to your overall DPS. Without talents you need 214 (or 26 rating) to reach the cap. After that’s done with you will want to focus on strength, crit, arp, haste, AP, agility, and armor in that order.
The short answer on Professions is, you will get the most out of choosing Blacksmithing and Jewelcrafting. That will give you the most versatility of adding whatever stats you are lacking to your char. The other professions aren’t that bad, if you cannot afford both JC and BS, you might try JC and mining until you want to train BS as it is the most expensive to power level.
There isn’t really a specific rotation, more of a priority system.
For single target it is
1. Killing Machine => Frost Strike
2. Keeping Frost Fever Up
3. Keeping Blood Plague Up
5. Blood Strike
6. Frost Strike
8. Horn of Winter when runes are down
Basically you are using highest dmg output abilities while refreshing your diseases just before they run out. It is better to let the disease run out and reapply asap than to reapply when they still have a few seconds left. This is a slight DPS gain, but a gain nevertheless.
2. Frost Fever UP
3. Blood Plague UP
4. Pestilence diseases to all targets
7. Blood Boil
8. Frost Strike
9. Horn Of Winter on Rune Cooldowns
Keep up diseases on all targets, use D&D when there are more than 3 targets otherwise not worth the runes.