Automatic Age Calculation in Word Document

You could use a REF field that would take you to a bookmark containing someone's date of birth. That would replace the ASK field in the complex field I gave earlier. I think that fields will be simpler long-term. No method will be completely automatic.

Again, calculations in Excel are far easier.

You may be better keeping the base data in an Excel spreadsheet and using MailMerge to bring values and information into a Word document. This could be done through a catalogue/directory mailmerge if you want or a regular letter mailmerge creating a new document.