Hi Mitch,
For that document, I used various formfields. You can access these via the 'Legacy Tools' button on the Developer tab's 'Contols' block. For the date calculation, I used a field from my Microsoft Word Date Calculation Tutorial, available at:
http://lounge.windowssecrets.com/index.php?showtopic=249902
or
http://www.gmayor.com/downloads.htm#Third_party
The tutorial shows how to do all sorts of date calculations using field coding (all of which entail fairly complex field coding).
Something that might be useful for you is to have a portion of the document into which you can freely insert additional text, etc. You'll note that, at the moment, the only thing you can do is to fill in the various fields. To create such a portion, insert two consecutive continuous section breaks. Then, when you apply forms protection to the document, leave that Section unprotected. See attached. The document now has three Sections and Section 2 is unprotected.