you need to remember to add in runic power attacks to your rotation, or spam them from a separate macro... also, the reset = 8 portion isn't going to allow you to even get close to the end of your macro, plain and simple 1.5 sec per global cooldown unless you have unholy presence active.

if you're worried about single target threat, that should be a non issue, diseases followed by scourge strikes should do the job nicely. Save your blood strikes till after however, as if you use the pestilence major glyph then you can use it to refresh diseases at the end of the rotation. Keep in mind, however, that plague strike has a naturally high threat modifier for you when in frost presence

If you're lookin for solid info go check out the dk info over at elitistjerks.com there's a ton of garbage and numbers to sift thru, but the reading is good, and all the info there is rather helpful =)