I have never used the =EXPORT tag, i searched for it in perlman:perlpod, but did not find any mention. Personally, i just prefer to use =HEAD and =ITEM:

=head1 EXPORTED THINGIES

=over 4

=item Keypressed

Blah blah blah...
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As for your second question about the use of EXPORT, here is what perlman:perlmodlib has to say:

Do NOT export method names!

Do NOT export anything else by default without a good reason!

Exports pollute the namespace of the module user. If you must export try to use @EXPORT_OK in preference to @EXPORT and avoid short or common names to reduce the risk of name clashes.

jeffa