use jpg files for images, with a quality of arount 70-80%. then you will really reduce file sizes of images, but you will barely notice a drop in quality. you will only really notice a difference at about 50% or below
you'll be making the email itself the newsletter, so you can either make it in Word or something, then copy and paste, or you can even set up a website with the newsletters, and maybe you can create some HTML code in the email that displays the web page (newsletter) inside the email. I don't know much HTML, but maybe someone here does.