This is a nice list, you'll have to be pretty lucky with your scatter dice however, otherwise you'll get shot to bits trying to get your slow crushers and letters into CC!HQ
Blood Thirster-270
-Unholy Might
Herald of Khorn-120
-Juggernaut
-Unholy Might
These are perfectly fine!
Elites
(9)Blood Crushers-360 (Herald of Khorn retinue)
Again, solid choice Maybe add an icon
Troops
Blood Letters-160
Blood Letters-160
Blood Letters-160
Blood Letters-160
You need to get some Icons on these guys, at least one, otherwise you'll be scaterring all over the place!
Heavy Support
Daemon Prince-205
-Wings
-Mark of Khorn
-Unholy Might
-Iron Hide
Daemon Prince-205
-Wings
-Mark of Khorn
-Unholy Might
-Iron Hide
Daemon Prince-205
-Wings
-Mark of Khorn
-Unholy Might
-Iron Hide
Okay drop the Mark of Khorne all its giving you is an extra attack and you already have 6 on the charge!
Daemonic Assault
Group 1 (preferred)
-Herald
-Blood Crushers
-Daemon Prince
-Daemon Prince
-Daemon prince
I would swap a daemon prince with some bloodletters, they should draw fire away from your crushers and Daemon princes.
Group 2
-Blood thirster
-Blood Lettersx4
If The Herald Starts the game attached to the blood crushers, Do they count as 1 unit when I'm deep striking them using the daemonic assault rule?
Correct me if I'm wrong but I'm sure that individual characters can only join a squad after they are on the board.