See http://word.mvps.org/FAQs/Formatting/NumberingFrontMatter.htm. Note that
if you want to omit the header (as opposed to just changing the numbering),
you must unlink the header in Section 2 from Section 1 and then leave the
header in Section 1 blank.

Yes It is possible. You need to put a section break where you want the
heading change to happen. Then on the header and footer toolbar. Click the
box called Link to Previous. This will then allow you to put a different
heading int each section.