Activision which publishes the Call of Duty games want to make as much money as possible so they release a new game about every year which is very difficult for one developer to do so they alternate.
It's already out.
it doesn't delete itself it got banned by treyach because its cheating you noob =@
There are various double xp windows, usually weekends when an event is happening, like a new map pack etc but there are also double weapon xp events for example now there's one because of E3 :)