Who are you sending your letter to? Have you already sent it? Is there a corporate head office you could contact? I think you have a lot of good ideas but Im wondering if your letter will affect your promotion hopes? (Not that I think you dont have valid concerns because I do--its just that sometimes, the upper levels dont appreciate anyone lower down pointing out the flaws in the company or its managers.) Obviously you arent Union. Thats a shame IMO.
Somehow you need to get ahold of the policies and procedures as well as a salary comparison and your job specs. Then you could compare/contrast what IS being done with what SHOULD be done.
Good Luck
ps: you might want to edit your original post, you've duplicated the entire thing!