You can have two primary professions (such as skinning, leatherworking, tailoring, blacksmithing, etcetera) and all of the secondary professions (Fishing, Cooking, First Aid and Archaeology).
Currently in Mists of Pandaria, the latest expansion to World of Warcraft, there are 90 levels.
There are roughly 9-10 million active subscriptions for World of Warcraft.
Assuming every single subscriber in World Of Warcraft plays which is ten million subscribers, then it is assumed that there are ten million people playing world of Warcraft.
too many...
It is estimated that around 9500 people join World of Warcraft every day.
There are many forums available on the official World of Warcraft website. WoW also has many "fansites" that can be found on the official website: http://www.worldofwarcraft.com Here is another website: http://www.fanaticsofwow.webs.com
In the past couple of years, there has been about 800,000 subscriptions canceled. This leaves World of Warcraft with about 10.2 million subscribers.
World of Warcraft had approximatly 9.3 million subscribers by the end of 2007. In January (2007) they had about 8 million.
Currently, as of August, 2012, there are 10.2 million active subscribers to World of Warcraft.
World of Warcraft initially sold 240,000 copies on its launch day in 2004.
Technically, private servers are illegal for World of Warcraft. Nevertheless, many people still play on private servers.
I'm assuming you mean "How many Gigabytes does World of Warcraft use or take up?" The answer is approximately 17.5GB. That is the size of my file atleast.