is it possible to have a header configuration only for the first page?

please be a bit more specific. Do you mean the header page (YES), the pagemenu bar, the divider bars, the entire header?

The entire header, because i would like to use the %image as a cover and the post anda the right ahd left sidebars as a "false" footer bar.

Just add the new widget area, drop the %image and put your image in one of the widgets.