Although it can seem a bit tedious to set up styles to use in your document(s), if you're doing much of anything more than a 1- or 2-page letter, you'll most likely find that it was time well spent. (And if you're looking at building a Table of Contents, this would certainly seem to be the case.) APPLYing styles is almost too simple, and they can be used in SO many ways, including the generation of a TOC. There's a lot of information available at http://www.microsystems.com/publications.htm,and at least one article that addresses your question exactly: http://www.microsystems.com/exp_pitfalls.htm
They also feature a link called "Dear Teresa" where you can submit specific questions.
The answer to your page number question involves the use of Section Breaks to isolate the parts that will use the different page numbering "themes". With the Section Breaks inserted where needed, you can define (and re-start, as needed) the page numbers to read as you wish.
For step-by-step instruction on any of the above, there are several good books available. For your purposes, you might look for one that focuses on using Word on something like the legal environment, where outline numbering and TOCs are used extensively.