Some ideas about orcs. Edit
Why, if Thrall in Eastern Alliance, there is no orcs here? Remove Dark Shamans from Horde and add them to EA. Another idea to give Orc Berserkers (because there are already grunts in Horde) - highly quick and strong unit, but weakly armored and easily beaten by ranged units. Another orc units may be Demolishers, Hunters with bows and Spearmen.
Another idea is to give new heroes to factions:
Farseers are greatest of shamans, granted with power of elements and gift of prophecy. As in Warcraft III.
Talent Trees: Spiritual, Restoration, Prophecies
Weapons: Lightning (Fire)
Mighty Draenei priests, Anchorites are masters both of healing and desroying.
Talent Trees: Healing, Exorcism, Discipline
Weapons: Holy Bolt (Holy)
Using fel holy power, Dark Priests are nice healers, also able to control minds of enemies and torturing their foes.
Talent Trees: Lifebinding, Mind, Torment
Races: Fel orc, orc
Weapons: Demonic bolts (Shadow)
A cunning and deadly opponent, Master Rogue can easily kill heroes, destroying enemy supply etc.
Talent Trees: Stalking, Stealth, Assassination
Races: Blood elf, Forsaken
Weapons: Daggers (Slashing)