Hi
1. A letter outlining how you have self-assessed your points is quite handy. I didn't attach one to my complete application, but I think its a good idea nonetheless.
2. Use the Visa Office Specific document checklist as a cover letter for your complete application. I think you already have your Visa Office specific checklist, but if you don't download it from : http://www.cic.gc.ca/english/information/applications/skilled-mission.asp
Goodluck // OB