Vilitch and Wulfrik seem ok, but by using them you are missing out on some of the really good options that
WoC characters have. Besides, Throgg is the best special character by far
Also, I've been really unimpressed with lore of slaanesh. Most people find the lore of tz or lore of nurgle to be more worthwhile,
ymmv.
I feel like you need some more meat on these bones. Cavalry just isn't as good as it used to be, and even Chaos Knights can have trouble with large blocks. I might suggest cutting one of the Knight units for another block. I also like flails on my khorne marauders and horsemen.