A cover letter simply introduces you and briefly may mention your goals. Other than intro and closing, maybe 1 paragraph.
See some cover letter samples:http://career-advice.monster.ca/resumes-cover...
Don't take anything out of your resume, but remember, in Canada, only name, address and other contact info (no gender, family circumstances..married or not, etc., no birthdate). This could all be seen as potential bias creators. Definitely no picture. 1 to 3 pages maximum. If you are just out of school, it will of course be shorter, no one expects you to have a huge list of experience. If you have been in the workforce for a long time, only go back 10 years, UNLESS you have earlier experience relevant to the job you are looking for.
The references, even from teachers and former employers, are more character references than anything else. (did she make personal calls half the day when working, were projects in on time, did she get along with others, etc.).
I have yet to go to an interview, or given someone else an interview, where "Zeugnisse" are required. This would be something you could later scan and email IF they really wanted them - which I doubt.
Also remember, if you are submitting your cover letter and email electronically, use some of the same key words in your cover letter as you find in the ad. It seems that HR software will pick that up and treat the submission more favorably - at least look at it, or so I'm told. Also, if you already know someone working where you are applying, be sure to mention that in your cover letter (with their agreement of course). This is also a bonus.