I honestly don't think you need such detailed cover letter. The officer will calculate the points irrespective of what you have in the letter and even if the he gets a different score, his score will not change based on your cover letter. In my opinion the cover letter is useful when you need to highlight a fact that is not quite as outlined in the online documentation. As an example, you are asked to get job duties on company letter head, however if you cannot obtain this, you may write a cover letter explaining why you can't and that your submitting self attested job duties to suffice.
Based on your cover letter, I don't see you highlighting any such anomalies, but instead outlining how you hope the visa office will evaluate your documents. I don't think in your case you even need a cover letter. That's my two cents, other seniors can weigh in.