Nothing really. Blizzard implemented a block in cross faction communication for a reason. That being, people were killing others and giving them grief about it. There is no way to communicate with the other side now and attempting to do so can get you banned from the game.
Human for the Alliance. Orc for the Horde
Nope. Where Alliance toons get rep with the Alliance Vanguard, Horde get rep with the Horde Expedition in Northrend.
horde
The Goblins that joined the horde joined because when they were fleeing there homeland of Kezan after Deathwing attacked it and caused the volcano to destroy the island, the alliance was in battle with a horde ship. The Human Captain had orders to destroy all ships in the area and leave no witnesses. So they attacked the ship the goblins were fleeing on. After the ship was sunk the survivors went to the near by islands called the Lost Isles. There the Goblin survivors found horde and alliance battling. Since the alliance attacked them at sea the Goblins found the horde camp and asked for help from the horde. In return the Goblins helped them defeat the alliance and rescue Thrall from the alliance who captured him. After this Thrall gave the Goblins a token to give to Grommash Hellscream in Org. And this is how they joined the Horde
I have both the guide and both have it's own pros and cons. It really comes down to whether you are playing the Alliance or the Horde since both have different quests and routes in WoW.
At the moment,there is about 9,000 horde on Aman'thul. Alliance have about 13,000, so there is about a ratio of 1.4 alliance to 1 horde.
Technically the Horde and Alliance both formed an alliance with the Death Knights after the Death Knights where betrayed by the Lich King.
As long as you are both Alliance or both Horde, and on the same server, you just have to travel to the other person's location and you can play with them.
Horde r00lz.
The hardest raid is no longer ulduar, the hardest WoW raid is Trial of The Grand Crusader 25 man heroic raid.
You obtain all of the flight licenses as of cataclysm at a trainer, nearby the flight masters of any major city , either horde or alliance.
Night Elves are in the Alliance faction.