OK! I've been playing for 6 years lol (not addicted, i dont play long) so heres my opinion.
FACTION - Alliance or Horde, whatever capital city you like more. They both have the same type of players. Alliance will have more medivial towns and more kinder looking characters. The Horde will have more interesting, creative areas with odd races and strange buildings.
CLASS - For PvE, I suggest the Warlock. Since Warlocks wear Cloth armor, they are weaker to attacks. Warlocks get a pet called the Voidwalker, which can "Tank" for you, meaning NPCs will normally attack the voidwalker instead of you. For PvP - I suggest the Mage. Mages can deal out alot of damage to other enemy players, also at higher levels they can place themselves within a bubble in which it takes 50% of the damage for you.
RACE - Since you want to be a clothy (cloth wearing class), I suggest Gnomes. They have more intellect, which gives them more mana. Mana is the resource that casters use to cast spells. Trolls are also a good race, they can use a racial ability that decreases casting speed for a couple of seconds. Undead are also nice for PvE since they can Cannibalize humanoid corpses, which gives them extra health and mana over time - if you play an undead, you no longer need to carry food or drink around. Race doesn't make TOO big of a difference, just play what you like.
Have fun. See you in Azeroth.