Word: changing the bottom rule on the 1st page of a 2 page table, then a different bottom rule on another table in the same document?

A section in Word means the whole document unless someone has added one or more section breaks (Page Layout tab | Breaks). In a single section, you can have up to three different headers, and three different footers; you accomplish that by selecting "Different first page" and "Different odd and even" on the Header & Footer Tools Design tab.

In a document with multiple sections, you can unlink headers and footers from their "neighbors" of the same type in the preceding section. Each type of header (footer), that is, first page, even page, or odd page, must be unlinked separately.

For "everything" on section formatting, take a look at http://word.mvps.org/faqs/formatting/workwithsections.htm; the general rules apply although the content hasn't been updated for the most recent versions of Word.

For assistance with creating a front matter in Word 2007 or later, see http://word.mvps.org/faqs/formatting/front_matter_2007.htm.

[Edit: corrected a typo]