Death Knight Requirements,What is the requirements for death knight?

Players will be able to create one Death Knight per server as long as they have at least one character that is level 55 or higher on that server. There are no racial limitations for creating your Death Knight, but PvP servers are still limited by faction (i.e. if you have an Alliance character on a PvP server, you cannot make a Horde death knight on that PvP server).

-------------------

Death Knights start at 55 so they are planning that you will just need a 55+ character on your account to create one. The 55+ character is not destroyed.

In doing this someone who is just starting the game cannot just start at level 55. As you stated Belfs and Draenei didn't need to be unlocked because no matter what they start at 55.