Applying to PhD position (Scandinavia): what should be included in personal letter
I believe the general advice given in the other question still applies to your situation. All those you mentioned are good to include, but they are mostly about yourself. To be more complete, you should also include reasons why you choose this particular school to do a PhD, which research topics interest you and why, as well as your aspirations for the future. Remember to be specific and try to relate as much as possible to the school you are applying to.