I have another template where header and footer shall look the same
except the page numbering that I would like to always have on the
outside when I print on both sides of the paper and put the papers in
a binder. Is there a way except for odd/even pages?


It is feasible using IF fields, but much simpler just to use different
even/odd headers and footers and duplicate the headers. If users editing the
document are capable of screwing up even/odd headers, then they'll screw up
fancy field coding too.