Specific Format - Letter of Intent

Content

Hi all - I have a letter that is currently sent through Taleo's correspondences, but our team wants to update the content.  Updates would include wording (easy to do), some formatting (size, bold/italic, color, etc.), but then there is some more complex updates they would like that include tables and calculations (adding two rows together).  Does anyone have an recommendations for how to proceed here?  I know if you know HTML coding it's helpful to get the right tweaks, but wondering if there are any suggestions you could offer?