Somewhat related: How to Deliver Resignation Letter To My Boss Who is Not Located on Site.
At the company I work for, I have a boss (the president of the company) and a supervisor. Unlike the related question above, I do not have the option of contacting my boss other than via e-mail. The boss will not be back in the country for another week.
On Monday, I will be accepting an offer for a new position, and I intend on putting in my two weeks immediately after to my supervisor. My questions are:
1) Should I e-mail my boss to let him know of my departure, or would letting my supervisor know suffice?
2) Should I include anything in a resignation letter other than a more formal version of "Dear X and Y, I will be leaving at date Z to work at [some type of company]. Regards, Me"? [I apologize if this question is too broad, but I have no experience in this whatsoever, and I have had inconsistent advice.]