The
size
you specify in the
font
tag is a number from 1 to 7, where 3 is the default of the browser (or mail client in this case). This attribute is also not supported in HTML 5 and should be avoided. See also
w3schools[
^].
It's better to use the style tag instead of the font tag, e.g.
<b style="font-size: 10px; font-family: 'Helvetica'; color: #B0B0B0;">some text</b>
Not sure what the deal is with the picture, you do have to send it with in the header of the mail with the correct name.