Every nontrivial file needs a license notice as well as the copyright notice. (Without a license notice giving permission to copy and change the file, the file is non-free.)
The package itself should contain a full copy of GPL in plain text (conventionally in a file named COPYING) and the GNU Free Documentation License (included within your documentation, so there is no need for a separate plain text version). If the package contains any files distributed under the Lesser GPL, it should contain a full copy of its plain text version also (conventionally in a file named COPYING.LESSER).
If you have questions about licensing issues for your GNU package, please write firstname.lastname@example.org.