Section breaks store the formatting (page layout, columns, and headers &
footers) of the preceding section; when you delete a section break, the
settings of the following section break will be applied.
So to answer your qustion: you will lose the current headers and footers
(that is, the ones now preceding the section break you plan to delete).
For detailed information, see
http://word.mvps.org/faqs/formatting/WorkWithSections.htm.
To delete multiple section breaks, you can use the Find and Replace dialog
box (use ^b for "Find what" and nothing for "Replace with"). But be sure to
take a look at the article mentioned above before you delete anything. In
particular, you may want to read the "If you really want to delete the
temporary section break ..." section.
