Okay, first things first, Beast herds and Bray Shamans can't take Marks of Tzeentch (In fact, Beast herds can't take any marks
). It sucks, I know, but the only regiments that can take Marks are Chariots, Minataurs, and Chaos spawn. Likewise, On the Charector front, only Beastlords, wargors, Doombulls, and Shaggoth Champion.
Also, Chao armour is a magic item-Only One Charector per army may have it, so I'd equip it to the Wargor-He's going to be doing most of the fighting.
However, the rest of your choices look solid. Tactics wise, Stick the two Shamans in the beast herds, to bring them on from ambush quicker. Detach if it looks like you're going into combat though-Bray Shamans may be tougher than you're average wizard, but they're still fairly weak in a melee.
Welcome to the Beasts of chaos, Honoured Foe-render!
