Welcome to Word and its field coding!
To see what's possible, check out my Microsoft Word Field Maths Tutorial, at:
http://windowssecrets.com/forums/sho...l=1#post320143
or
http://www.gmayor.com/downloads.htm#Third_party
Formatting, FWIW, is controlled via switches you can add to the fields.
As for the updating, it's only truly automatic when you use a document with formfields for the data entry and check their 'calculate on exit' property. You can also ensure they're correct at print time by checking Word's 'update fields before printing' property.
PS: For cross-posting etiquette, please read:
http://www.excelguru.ca/content.php?184