As to your suggestion regarding the default font size; changing the content.css file worked great! I set it as follows;
font-family: Times New Roman, Times, serif;
At first I only changed the font size, and the email was correct, but the editor display showed a different font. Then I changed the Font-family in content.css and both were in agreement.
The email template already called out the size I wanted but until I changed the content.css, the size in the email was wrong.