I have made templates on salesforce for my project to, so I can do this task efficiently with the required timelines which you have mentioned. I have made so many html templates as well as visual force templates what ever the requirement would I will do that accordingly, recently I was working for non profit organization and they want from me to make email template to send email to each donor of consolidate donations on yearly basis which retires relation ships which cannot be accomplished by merge fields so I have made a visual force page which calculates its over donation of the particular year which they have searched and by clicking the button the template will be send to the donor