well, unfortunately you're over your daemonic pts limit... daemonic gifts, gifts of the gods and daemon weapons all count against your 100pts limit. (3rd printing change i believe!)
just drop d.armour... you're going to be shot at by lascannons, plasma, lances & rail guns so you really won't get much use out of that armour anyways! trust to your invulnerable save.
also, i'd drop warp flame from your preds as they're ment to sit back and shoot... they've got enough protection in the form of mutated hull!
if you really want them to be nutty, try for parasitic possession! i can't think of anyone who won't moan when supposidly destroyed lascannons grow back!!!
you might want to look at adding some daemons in place of a squad of chaos marines, simply to bulk out your numbers abit...
- flamers have insane fire power and are easily expendable! your opponent will go to great lengths to get rid of them simply because each one has the equivalent of a shorter-ranged psychic heavy bolter!!!
- screamers offer a superb fast assault unit, and can be used to quickly engage the enemy, plus they have the furious assault skill! granted they won't survive, but it's better having your opponent wast valuable resources dealing with them instead of nuking your much more pricey marines!
and finally, you should look into getting some psychic powers for your prince!
- gift of chaos with warp focus can catch an opponent off guard when you start turning their models into chaos spawn at 3-8" range!
- wind of chaos can thin out aproching hoards...
- twisting path can go hand in hand with a support vehicle with a blasphemous rune!
- avoid the minor psychic power as they're really not that great and far too random as well...
as for the chosen of ahriman. most tournaments don't allow them (if i recall, they are still trial rules...)
but for friendly play, as long as you ask/inform your opponent and have a copy of their rules, i really can't see very many people not letting you use them! (they're really just expensive lieutenants who can teleport a unit with them...)
hope this helps,
cheers!