The third slot will open after you've created a second character. The fourth slot will open after you've created the third.Originally Posted by RivetHead. Go to original post
Hope this helps, and welcome to the forums!
Creation does indeed ask if you want to opt for hardcore or normal.
I keep my 4th slot is for a hardcore one for those moments when I stupid enough to think that the game won't randomly punt me away from european servers mid mission because contending with lag and bullet sponging is somehow the pinnacle of a gameplay experience.